Practice A.3 Work, energy and power with authentic IB Physics exam questions for both SL and HL students. This question bank mirrors Paper 1A, 1B, 2 structure, covering key topics like mechanics, thermodynamics, and waves. Get instant solutions, detailed explanations, and build exam confidence with questions in the style of IB examiners.
A sledge carrying a box slides down a smooth snow slope, starting from rest at the top. The slope curves smoothly until it becomes horizontal, as shown.
Assume there is no friction between the sledge and the snow. Air resistance is negligible.
State the energy transformations taking place as the sledge descends the slope.
The sledge and box together have a mass .
At the top of the slope, the sledge is at a vertical height above the horizontal surface. Determine an expression for the speed of the sledge when it reaches the horizontal snow region.
Explain why the normal force exerted by the snow changes as the sledge moves down the curved part of the slope.
After reaching the horizontal region, the sledge travels a distance before coming to rest. The coefficient of dynamic friction between the sledge and the snow in this region is . Draw a free-body diagram showing the forces acting on the sledge while it is moving horizontally.
Determine an expression for the distance in terms of , and .
A ball of mass is released from rest at a height above the ground. It slides down a smooth curved surface and rises up to a height on the opposite side.
Assume there is no friction except at the bottom of the curve where some mechanical energy is lost.
State the principle of conservation of mechanical energy for a frictionless system.
Outline why the ball does not reach the original height on the opposite side.
Assuming no friction except at the bottom, show that the expression for the mechanical energy lost as the ball moves from height to height .
If , and , calculate the energy lost.
Calculate the percentage of mechanical energy lost during the motion.
A hoist lifts a load vertically in . The motor providing the lift consumes a constant current of at . What is the efficiency of the system?
A spring with spring constant is compressed by and used to launch a cart along a horizontal surface with of the energy lost due to friction. What is the final speed of the cart?
A diver of mass steps off a diving board above the water. Assuming of the gravitational potential energy is lost to air resistance before hitting the water, what is the diver's speed just before entry?
At a theme park, a rollercoaster car is pulled from rest up to a height of in along a frictionless track. If the motor driving the lift system has a maximum power output of , is the motor powerful enough and how much power would actually be needed?
A machine lifts a load vertically upward at a constant speed of . The gravitational field strength is .
Calculate the power output required to lift the load at this constant speed.
Determine the work done by the machine in .
Explain why the load does not gain kinetic energy even though the machine is doing work.
A pump raises of water vertically through a height of in . Assume all the useful power goes into lifting the water.
Calculate the gravitational potential energy gained by the water.
Determine the useful power output of the pump.
The actual power consumed by the pump is . Calculate the efficiency of the pump.
Explain what happens to the missing energy not used to raise the water.
A car is travelling at a constant speed of . Its engine takes of power and the average resistive force acting on the car is . What is the efficiency of the engine?
A power station generates of electrical power by burning fuel with an energy density of . The power station operates with an efficiency of .
Calculate the useful energy output per second.
Determine the total energy input per second from the fuel.
Calculate the mass of fuel burned per second.
Discuss two ways to improve the efficiency of the power station.