Forces

An object with mass $10\,\text{kg}$ keeps five identical bags of rice in balance on a uniform beam. Two additional bags, each identical to the first five, are then placed with them. The mean position of the bags on the beam stays the same. What mass is required now to balance the bags?

Feb/March 2016

The diagram illustrates a rod that is not balanced. Two loads X and Y may be shifted along the rod. The rod rotates clockwise, as indicated. Which action could allow the rod to balance?

Feb/March 2016

A box is being raised by a fork-lift truck. The weight of the box is $3000\,\text{N}$. The force applied by the fork-lift truck to the box is $3500\,\text{N}$ acting vertically upwards. What is the resultant vertical force on the box?

Feb/March 2016

A spring follows Hooke’s law. Which graph is produced when the spring’s extension is plotted against the load applied?

Feb/March 2016

Fig. 3.1 shows a see-saw. When it is not being used, the see-saw is horizontal. A small child is seated on one seat of the see-saw. This produces a turning effect about point P.

Feb/March 2016

An engine in a car produces a forward force of $100\text{ kN}$ on the vehicle. The combined resistive force acting on the car is $20\text{ kN}$. What is the resultant force on the car?

Feb/March 2017

A skydiver leaps out of a helicopter that is stationary and soon attains a constant vertical speed. She then deploys her parachute. Which statement about the falling skydiver is correct?

Feb/March 2017

State the conditions that must hold if the object (i) does not accelerate, (ii) does not rotate.

Feb/March 2017

The diagram depicts a bird flying through the air. It is moving horizontally towards the right. In which direction does air resistance act on the bird?

Feb/March 2018

A car moves along a straight, level road. The speed-time graph is shown. During which labelled section of the journey is the resultant force on the car zero?

Feb/March 2018

The diagram illustrates a uniform metre rule in equilibrium about its centre point. What is the weight $W$ positioned at the $20\,\text{cm}$ mark?

Feb/March 2018

A wooden plank is balanced in equilibrium on two rocks that are positioned on opposite sides of a narrow stream. Three forces $P$, $Q$ and $R$ act on the plank. What relationship exists between the magnitudes of the forces?

Feb/March 2018

A parachutist is descending through the air at terminal velocity. Which of the following statements about the parachutist is correct?

Feb/March 2018

The diagram depicts a bird in flight. The bird is moving horizontally towards the right. In which direction does air resistance act on the bird?

Feb/March 2018

A stone with mass $0.12\,\text{kg}$ is launched from a catapult. Its velocity changes from $0$ to $5.0\,\text{m s}^{-1}$ over $0.60\,\text{s}$. What is the average resultant force acting on the stone during the launch?

Feb/March 2018

Rod XY is uniform and has a weight of $2.0\,\text{N}$; its length is $80\,\text{cm}$. The rod is supported by a thread attached $20\,\text{cm}$ from end X. A $5.0\,\text{N}$ weight is hung from end X. A student places a $6.0\,\text{N}$ weight on the rod so that equilibrium is obtained. How far from end X is the $6.0\,\text{N}$ weight?

Feb/March 2018

A wooden plank is balanced in equilibrium on two rocks positioned on opposite banks of a narrow stream. Three forces $P$, $Q$ and $R$ act on the plank. What is the relationship between the sizes of the forces?

Feb/March 2018

Fig. 3.1 displays the load-extension graphs for two springs, A and B. The vertical axis gives load in N, while the horizontal axis shows extension in mm. The two straight-line plots are labelled spring A and spring B.

Feb/March 2018

Complete the statement by inserting the missing words in the blank spaces. The moment of a force about a pivot is equal to ................ multiplied by ................

Feb/March 2018

The spring’s extension/load graph is shown below. The unstretched length of the spring is $15.0\,\text{cm}$. When an object with unknown weight is hung from the spring, the spring’s length becomes $16.4\,\text{cm}$. What weight does the object have?

Feb/March 2019

The diagram shows a wooden beam with two forces acting on it. In which direction will the beam move?

Feb/March 2019

A graph showing extension against load for a spring is shown. The spring’s unstretched length is $15.0\,\text{cm}$. When an object with an unknown weight is hung from the spring, the spring’s length becomes $16.4\,\text{cm}$. What is the weight of the object?

Feb/March 2019

A $2.0\,\text{kg}$ box is dragged along the floor by a $6.0\,\text{N}$ force. The frictional force on the box is $1.0\,\text{N}$. What is the box's acceleration?

Feb/March 2019

Which moving object experiences a resultant force acting on it?

Feb/March 2019

A load hangs from a spring, as illustrated in Fig. 3.1. Two arrows show the vertical forces on the load. The spring and the load remain stationary.

Feb/March 2019

State three ways in which a force may alter the motion of the object.

Feb/March 2019

A car moves on a horizontal road at a constant speed. There are three horizontal forces acting on the car. The diagram shows two of these forces. What are the magnitude and direction of the third horizontal force acting on the car?

Feb/March 2020

A force $F$ acts on a spanner, as shown. Which change increases the moment of $F$ about the centre of the nut?

Feb/March 2020

A ball is released from rest and drops through the air towards the ground. The diagram shows two forces acting on the ball. While the ball is falling, the air resistance increases. Which statement is correct?

Feb/March 2020

A car moves at constant speed along a horizontal road. There are three horizontal forces acting on the car, and the diagram shows two of them. What are the magnitude and direction of the third horizontal force acting on the car?

Feb/March 2020

An athlete of mass $70\,\text{kg}$ is training by doing press-ups while carrying a load on his back. The diagram indicates the perpendicular distances concerned. The athlete’s centre of mass is $C_M$ and the centre of mass of the load he carries is $C_L$. The load has a mass of $6.0\,\text{kg}$. What upward force is exerted by his two arms?

Feb/March 2020

A 50 cm rule is balanced with its midpoint as the support point. A force of 8.0 N acts 10 cm from one end of the rule. Fig. 2.1 illustrates the arrangement.

Feb/March 2020

The diagram depicts a bird flying through the air. The bird is moving horizontally to the right. In which direction does air resistance act on the bird?

Feb/March 2021

A rocket is moving vertically upwards. Three vertical forces act on it. The thrust acts upwards and is equal to $100\,000\,\text{N}$. The weight acts downwards and is equal to $80\,000\,\text{N}$. What is the force of air resistance on the rocket when it is moving upwards at constant speed?

Feb/March 2021

Two people $X$ and $Y$ are seated on a see-saw, as illustrated. $X$ has a weight of $400\,\text{N}$ and is positioned $1.5\,\text{m}$ from the pivot. The see-saw itself weighs $300\,\text{N}$ and its weight acts through the pivot. With the see-saw in balance, the pivot exerts an upward force of $900\,\text{N}$ on the see-saw. Determine the weight of person $Y$ and the distance from the pivot at which he is seated?

Feb/March 2021

An object can turn about point P. A student fastens one end of a string to a peg on the object. He then pulls on the string with a force $F$. What is the moment of the force $F$ about point P?

Feb/March 2021

Fig. 3.1 represents the forces acting on a uniform beam that is balanced. The beam has its pivot at the centre. Fig. 3.1 shows: a pivot at the centre; a downward force of 5.2 N applied 6.0 cm to the left of the pivot; a downward force of 8.1 N applied 2.0 cm to the right of the pivot; an upward force P applied 2.0 cm to the left of the pivot.

Feb/March 2021

State what the moment of a force about a point means.

Feb/March 2021

An object moves upwards at constant speed in water. Three vertical forces act on it: the weight $W$, the drag force $D$, and the upward force $U$. Which diagram shows the size and direction of the vertical forces acting on the object?

Feb/March 2023

Which force generates heating when it is in contact with a moving object?

Feb/March 2023

The metre rule is in equilibrium at its midpoint. It still stays balanced when a $3.0\,\text{N}$ load is suspended from the $40\,\text{cm}$ mark and another load is suspended from the $80\,\text{cm}$ mark. Determine the weight of the second load.

Feb/March 2023

A student records the length of a spring. She then hangs different weights from the spring. For each weight, she measures the spring’s length. Her results are given in the table. What extension does the spring have when a weight of $3.0\,\text{N}$ is attached to it?

Feb/March 2023

As the car’s speed rises, the drag force also rises. When the speed is $20\,\text{m s}^{-1}$, the total drag force is $400\,\text{N}$. The car has a mass of $1200\,\text{kg}$ and a constant driving force of $700\,\text{N}$. Which of the following statements about the car’s acceleration at $20\,\text{m s}^{-1}$ is correct?

Feb/March 2023

An object moves upwards vertically at a steady speed through water. Three vertical forces act on it: the weight $W$, the drag force $D$, and the upward force $U$. Which diagram shows the directions and sizes of the vertical forces acting on the object?

Feb/March 2023

Two boys who have the same weight are seated on one side of a see-saw, as illustrated. On the opposite side sits their father, whose weight is $1000\,\text{N}$. The see-saw is in balance and is used in a way that makes it move up and down. In one stage of the motion, the father moves downward by a distance of $40\,\text{cm}$. During that same time, the boy closest to the pivot moves upward by $20\,\text{cm}$, while the other boy moves upward by $80\,\text{cm}$. What is the weight of each boy?

Feb/March 2023

A student measures the length of a spring. Next, she hangs different weights on the spring. For each weight, she records the spring’s length. Her results are shown in the table. What is the extension of the spring when a weight of $3.0\,\text{N}$ is attached to it?

Feb/March 2023

Use the graph to find the spring length when the student applies a load of $8.0\,\text{N}$ to the spring.

Feb/March 2023

Fig. 2.1 depicts a ship carrying containers. The diagram labels the ship, the containers and the water.

Feb/March 2023

A rocket is moving straight up. It is acted on by three vertical forces. The thrust acts upwards and has a magnitude of $100\,000\,\text{N}$. The weight acts downwards and has a magnitude of $80\,000\,\text{N}$. What is the air resistance force on the rocket while it is moving upwards at a constant speed?

Feb/March 2024

The diagram illustrates a solid object resting on a horizontal surface, with two forces acting on it. What is the resultant force on the object?

Feb/March 2024

A beam of negligible weight is in equilibrium on a pivot, as illustrated. Forces P, Q and R are acting on the beam. Which equation is correct?

Feb/March 2024

What does the term moment of a force mean?

Feb/March 2025

The diagram illustrates three forces acting on an object. What is the magnitude of the resultant force on the object?

Feb/March 2025

A load-extension graph for a material is shown. Which point shows the limit of proportionality?

Feb/March 2025

Fig. 3.1 presents a central cross-section of a solid cone alongside a central cross-section of a solid cuboid. In Fig. 3.1, the cone and the cuboid are shown resting on the ground. The solid cone is the more stable object. The symbol x marks the location of the centre of gravity for each object.

Feb/March 2025

Fig. 1.1 presents a force-extension graph for a spring.

Feb/March 2025

Which option gives an example of a force?

May/June 2016

The diagram shows an object with weight $W$ and an object with weight $Z$ in balance on a uniform metre rule. Which equation linking $W$, $Z$, $a$ and $b$ is correct?

May/June 2016

A boy throws a stone. After leaving the boy’s hand, the stone travels straight upwards. Air resistance is negligible. How should the force acting on the stone be described immediately after it leaves the boy’s hand?

May/June 2016

A car moves along a straight road. The speed-time graph for this trip is shown. During which labelled section of the trip is the resultant force on the car zero?

May/June 2016

The diagrams display four objects A, B, C and D. On each diagram, the centre of mass $M$ is shown. Which object is not in equilibrium?

May/June 2016

A feather is falling through the air. Its speed downward remains constant. Which statement about the feather is correct?

May/June 2016

A satellite moves round the Earth above the atmosphere at a steady speed. The diagram shows the satellite at one point in its circular path around the Earth. Which labelled arrow indicates the direction of the resultant force on the satellite at the position shown?

May/June 2016

The diagrams illustrate three uniform beams P, Q and R, each with a pivot at its centre. The two forces acting on each beam are also shown. Which beams turn clockwise?

May/June 2016

The diagram depicts a non-uniform beam with weight $120\ \text{N}$, and it is pivoted at one end. The beam remains in equilibrium because of force $F$. What is the value of force $F$?

May/June 2016

An object experiences a $3\ \text{N}$ force and a $4\ \text{N}$ force. Each diagram displays these two forces. Which diagram also represents the resultant $X$ of these forces?

May/June 2016

A car’s engine provides a driving force of $5000\ \text{N}$ on the car. Resistive forces $R$ also act on the car, as shown. The car has a mass of $800\ \text{kg}$ and an acceleration of $1.0\ \text{m s}^{-2}$. What is the value of $R$?

May/June 2016

A plank XY is resting on the ground. A load of $120\,\text{N}$ is put on it $0.50\,\text{m}$ from end X, as illustrated. End Y is then raised from the ground. The upward force required for this is $65\,\text{N}$. In the diagram, $W$ represents the weight of the plank acting through its midpoint. What is the value of $W$?

May/June 2016

A boy leaps from a high board into a swimming pool. Fig. 2.1 shows the forces acting on the boy at one moment during his fall.

May/June 2016

Fig. 3.1 presents a girl and a boy on a see-saw. The diagram indicates that the girl has weight 300 N and is 2.4 m from the pivot, whereas the boy has weight W and is 1.6 m from the pivot. The see-saw turns about the log.

May/June 2016

Fig. 3.1 depicts a girl and a boy on a see-saw. The girl is 2.4 m from the pivot, while the boy is 1.6 m from the pivot. The girl’s weight is 300 N.

May/June 2016

State why force is considered a vector quantity.

May/June 2016

A car moves forwards on a straight horizontal road. The only forces acting on it horizontally are shown. Each arrow’s length shows the size of the force it represents. What effect do these forces have on the car’s motion?

May/June 2017

The midpoint of a uniform metre rule is supported on a pivot. A load with weight $3.0\,\text{N}$ is positioned at the $70\,\text{cm}$ mark. An upward force $F$ is applied at the $80\,\text{cm}$ mark. The rule is in equilibrium. What is the magnitude of $F$?

May/June 2017

The diagram shows an object that is being acted on by two forces. What is the magnitude of the resultant force on the object?

May/June 2017

A student is required to investigate the extension of a spring with the apparatus illustrated in the diagram. Which additional piece of equipment is required?

May/June 2017

A skydiver has reached terminal velocity. He then opens his parachute. What occurs to the skydiver as the parachute opens?

May/June 2017

A ball weighing $1.2\,\text{N}$ is falling through the air at terminal velocity. A sudden gust of wind applies a horizontal force of $0.5\,\text{N}$ to the ball from the left. Which diagram illustrates the resultant force on the ball while the wind is blowing?

May/June 2017

The diagram depicts a uniform bridge that is $4.0\,\text{m}$ in length and has a weight of $10\,000\,\text{N}$. The bridge is pivoted at one end. At the other end, a force is increased slowly until the bridge just starts to rise. What is the lifting force when the bridge begins to move upwards?

May/June 2017

Which pair has both quantities expressed in newtons?

May/June 2017

An unstretched spring that follows Hooke’s Law has a length of $10\,\text{cm}$. A load with weight $20\,\text{N}$ is attached to the spring. After this, the spring’s length becomes $36\,\text{cm}$. Calculate the spring constant $k$ for the spring.

May/June 2017

A car moves forward on a level road that is straight. Only the horizontal forces acting on it are displayed. The size of each force is represented by the length of each arrow. What effect do these forces have on the car’s motion?

May/June 2017

The diagram represents a wooden beam with weight $20\,\text{N}$. Its centre of mass is marked $M$. A pivot is positioned at one end of the beam. An upward force, $F$, holds the beam in a horizontal position. What is the magnitude of $F$?

May/June 2017

The diagram illustrates an object experiencing the effect of two forces. What is the magnitude of the resultant force on the object?

May/June 2017

The diagram illustrates a man keeping a sack and barrow at rest. He exerts a vertical force on the handle. The centre of mass and the weight of the sack and barrow are indicated. The wheel functions as the pivot. What is the magnitude of the vertical force applied by the man?

May/June 2017

The diagram shows that the only forces acting on an object are $F_1$ and $F_2$. The length of each arrow indicates the magnitude of the force. The resultant force on the object is $R$. Which vector diagram shows the addition of forces $F_1$ and $F_2$ to give $R$?

May/June 2017

Fig. 3.1 depicts a tyre suspended from the branch of a tree. The labels shown are: branch, rope, tyre, and point P on the branch where it joins the tree. The horizontal distance from the tree trunk to the rope is 2.5 m.

May/June 2017

Fig. 3.1 depicts a large sunshade. The labelled features on the diagram are sunshade, arm, pivot, support, and base. The arm carrying the sunshade turns about the end of a support.

May/June 2017

A car is travelling in a straight line along a level road. The engine exerts a forward force on the car. A second force of the same magnitude acts on the car because of resistive forces. Which statement describes what happens?

May/June 2018

A hole is made in a square tile. The diagram shows the tile suspended from a nail. Where is the tile’s centre of mass?

May/June 2018

A man is holding a short ladder in four different positions. The ladder’s weight produces a moment about the man’s shoulder. For which position is the moment the largest?

May/June 2018

Which characteristics of an object may be altered by a force?

May/June 2018

A man supports a ladder in four different positions, with the ladder turning about his shoulder as a pivot. The ladder’s weight produces a moment about the man’s shoulder. In which position is the moment largest?

May/June 2018

At what point does an object descending vertically through the air attain terminal velocity?

May/June 2018

A balloon and a mass are fixed to a rod that can turn about the pivot at P. The balloon contains helium, which is less dense than air, so it exerts an upward force on the rod. The rod is horizontal and remains at rest. Which action makes the rod turn clockwise?

May/June 2018

A car travels along a straight path on a level road. The engine exerts a forward force on the car. A second force, equal in magnitude, acts on the car because of resistive forces. Which statement correctly describes what occurs?

May/June 2018

At what point does an object falling straight down through the air attain terminal velocity?

May/June 2018

An object slows from $25.0\,\text{m s}^{-1}$ to $5.0\,\text{m s}^{-1}$ over a time of $4.0\,\text{s}$. Its mass is $50\,\text{kg}$. Determine the resultant force acting on the object.

May/June 2018

A beam is pivoted at one end, as shown. Its weight is $6.0\,\text{N}$ and acts at point $X$, which is $40\,\text{cm}$ from the pivot. A force of $4.0\,\text{N}$ is exerted on the beam so that it remains balanced in a horizontal position. In what direction is the $4.0\,\text{N}$ force applied, and at what point does it act?

May/June 2018

A spacecraft is moving through space with no resultant force and no resultant moment acting on it. Which statement about the spacecraft is correct?

May/June 2018