Physics 5054 · O Level · Balanced and unbalanced forces
Balanced and unbalanced forces — practice question
Seen from above, two small tugboats are towing a large ship in a harbour. Fig. 1.1 gives the directions of the forces acting on the ship.
Fig. 1.1 (not to scale) shows a ship being towed by two tugboats. Each tugboat applies a force of 49 kN to the ship. The forces are placed symmetrically at angles of 20^{\circ} above and 20^{\circ} below the centre line of the ship.
(a)[3]
Use a graphical method to find the resultant of these two forces and state the scale that was used.
(b)[2]
The ship’s engines are switched off and the water in the harbour is still. The ship is travelling in a straight line in the direction of the total force from the tugboats, and its speed is constant. Explain, in terms of the forces acting, why the ship is moving in a straight line at constant speed.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Use a scale of at least 1.0 cm : 10 kN” …