Same force, different mass
A 600 N resultant acts separately on carts of mass 150 kg and 300 kg. Calculate each acceleration and explain the difference using inertia.
TOPIC 3 · CIE PRACTICEDefine the system.
Define the system.
Track every force.
Each problem stays visible. Attempt it with a diagram and sign convention, open a modelling hint if needed, then compare every step with the worked solution.
Lift acceleration
A 70 kg passenger stands on a scale in a lift accelerating upward at 1.5 m s⁻². Calculate the scale reading.
Car and trailer interaction
A car pulls a trailer forward. Identify the Newton’s-third-law partner of the force exerted by the car on the trailer, and explain why the pair does not cancel.
Safer stopping
A 0.18 kg ball moving at 25 m s⁻¹ is brought to rest. Calculate its momentum change and the average force when stopping takes (a) 0.015 s and (b) 0.060 s.
Explosion from rest
A stationary 12 kg object separates into a 5.0 kg part moving at 8.0 m s⁻¹ east and a 7.0 kg part. Find the second part’s velocity.
Parachute sequence
Explain how weight, drag, resultant force, acceleration and speed change from the instant a parachute opens until the new terminal speed is reached.
Do the trolleys stick?
A 2.0 kg trolley moving at 5.0 m s⁻¹ hits a stationary 3.0 kg trolley. They move together. Find their common velocity and the kinetic energy transformed.
Force–time collision
A force on a 0.40 kg ball rises uniformly from zero to 120 N in 0.020 s, then falls uniformly to zero over the next 0.030 s. The ball initially moves at −3.0 m s⁻¹. Find its final velocity.