CAIE A-Level Physics 3.1.3 Linear Momentum p = mv

Practise defining and calculating vector momentum p = mv, comparing magnitude and sign in motion or collisions and checking direction and units.

Exam points

Define and calculate linear momentum p=mv with correct direction and units.
Use momentum in a moving-body or collision context, comparing magnitude and sign.
Interpret how mass or velocity changes affect momentum and check the vector direction.

[Maximum number: 2]

A child's toy uses the spring in (a) to launch a ball of mass 0.020 kg vertically into the air. The ball is initially held against one end of the spring which has a compression of 0.045 m . The spring is then released to launch the ball. The kinetic energy of the ball as it leaves the toy is 0.72 J .

Determine the initial momentum of the ball as it leaves the toy.

momentum =

$E=\frac{1}{2} m v^{2}$

C1

p=m v

C1

$\begin{aligned} 0.72=1 / 2 \times 0.020 \times v^{2} \text { and } p=0.020 \times v p=0.17 \mathrm{Ns} \end{aligned}$

A1

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3.1.3—Linear momentum as the product of mass and velocity question 1