Physics 9702 · AS & A Level · Kinematics of uniform circular motion

Kinematics of uniform circular motion — practice question

(a)[2]

Using velocity and acceleration, describe the uniform circular motion of an object.

(b(i))[1]

State an expression, in terms of $R$ and $\omega$, for the ball’s speed $v$.

(b(ii))[2]

Determine an expression, in terms of $v$ and $\omega$, for the ball’s centripetal acceleration.

(c(i))[1]

The ball in (b) is shown in Fig. 1.1, with line OB making an angle $\theta$ to line OP. Determine an expression, in terms of $R$ and $\theta$, for the shadow’s displacement $x$ from P.

(c(ii))[1]

At time $t = 0$, the value of $\theta$ is zero. State an expression for $\theta$ in terms of $\omega$ and $t$.

(c(iii))[1]

Use the results from (c)(i) and (c)(ii) to show that $x$ is given by $x = R \sin \omega t$.

(c(iv))[1]

Explain, using the equation in (c)(iii), why the shadow of the ball on the screen can be modelled as simple harmonic motion.

(d(i))[1]

The circular motion of the ball in Fig. 1.1 has a diameter of $0.46\,\text{m}$ and an angular speed of $1.9\,\text{rad s}^{-1}$. For the simple harmonic motion of the shadow of the ball in Fig. 1.1, calculate the amplitude.

(d(ii))[2]

The circular motion of the ball in Fig. 1.1 has a diameter of $0.46\,\text{m}$ and an angular speed of $1.9\,\text{rad s}^{-1}$. For the simple harmonic motion of the shadow of the ball in Fig. 1.1, calculate the period.

(d(iii))[2]

The circular motion of the ball in Fig. 1.1 has a diameter of $0.46\,\text{m}$ and an angular speed of $1.9\,\text{rad s}^{-1}$. For the simple harmonic motion of the shadow of the ball in Fig. 1.1, calculate the maximum acceleration.

(e)[1]

On Fig. 1.1, draw, and label with the letter A, the position of the shadow on the screen when the shadow has its maximum positive acceleration.

Worked solution & mark scheme

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