Pulling a suitcase
A 65 N force pulls a suitcase 18 m at 35° above horizontal. Friction is 20 N. Find the work by the pull, by friction and the net work.
TOPIC 5 · CIE PRACTICEName the stores.
Name the stores.
Track the transfer.
Attempt each visible problem, use a modelling hint if needed, then reveal the detailed energy account.
Variable spring force
Force increases linearly from 0 to 40 N over 0.20 m. Find the work and average force.
Braking a car
A 1000 kg car slows from 24 m s⁻¹ to 10 m s⁻¹. Find the change in kinetic energy and net work.
Two routes uphill
A 75 kg climber reaches a point 420 m vertically above the start by a 1.2 km path. Find the GPE increase.
Slide with resistance
A 4.0 kg object starts from rest 6.0 m high and arrives at 8.0 m s⁻¹. Find energy dissipated.
Lift motor
A 900 kg lift rises at 2.5 m s⁻¹ against 1200 N resistance. Find motor power.
Pump efficiency
A pump takes 2.4 kW and lifts 35 kg of water each second through 4.5 m. Find efficiency.