Physics 9702 · AS & A Level · Simple harmonic oscillations

Simple harmonic oscillations — practice question

(a)[2]

Describe the motion of an object in uniform circular motion in terms of velocity and acceleration.

(b(i))[1]

State an expression, using $R$ and $\omega$, for the speed $v$ of the ball.

(b(ii))[2]

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

(c(i))[1]

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

(c(ii))[1]

At time $t = 0$, $\theta$ is zero. State an expression for $\theta$ using $\omega$ and $t$.

(c(iii))[1]

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

(c(iv))[1]

Explain, with reference to the equation in (c)(iii), why the motion of the shadow of the ball on the screen may be modelled as simple harmonic motion.

(d(i))[1]

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

(d(ii))[2]

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

(d(iii))[2]

The ball in Fig. 1.1 moves in a circle of diameter $0.46\,\text{m}$ and angular speed $1.9\,\text{rad s}^{-1}$. 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 the shadow’s position on the screen when it has maximum positive acceleration, and label it A.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: velocity and acceleration each have constant magnitude

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