Energy
Which of the following is the correct list of all seven energy stores recognised in the CIE syllabus?
A car brakes and comes to a stop on a dry road. Which statement correctly describes the main energy transfer?
A student writes: “When a battery powers a lamp, chemical energy is converted into light energy and heat energy.” State what is wrong with this description according to CIE examination requirements. Which corrected statement would gain full marks?
Calculate the kinetic energy of a 0.40 kg ball travelling at 5.0 m s⁻¹.
A truck of mass 3000 kg has a kinetic energy of 375 000 J. Determine the speed of the truck.
A teacher lifts a 1.5 kg textbook from the floor and places it on a table. Which transfer pathway best describes how energy is moved from the teacher’s chemical store to the gravitational potential store of the book?
A stone of mass 0.25 kg is dropped from rest at a height of 5.0 m. Assuming no air resistance and using g = 9.8 N kg⁻¹, calculate the speed of the stone just before it hits the ground.
The principle of conservation of energy states that energy cannot be created or destroyed. A filament lamp is supplied with 80 J of energy each second. It produces 4 J of useful light. Calculate the wasted energy and identify the store it is transferred to.
A cyclist doubles her speed while keeping the same mass. What happens to her kinetic energy?
A crane lifts a 400 kg load through a vertical height of 15 m. Use g = 10 N kg⁻¹. What is the minimum energy transferred by the crane motor?
Which of the following correctly identifies an energy store rather than a transfer pathway?
A 1500 kg car travels at 72 km h⁻¹. Calculate its kinetic energy.
A Sankey diagram for a diesel engine shows an input of 2000 J of chemical energy. The useful kinetic energy output is 600 J, and 1100 J is wasted as internal (thermal) energy of the exhaust gases. Calculate the energy transferred to the internal (thermal) store of the engine block.
A student says that when a ball is thrown upward, energy is “used up” as it slows down. Which statement best corrects this misconception?
A roller coaster car of mass 800 kg is at the top of a hill 20 m above the ground, travelling at 5.0 m s⁻¹. Using g = 10 N kg⁻¹ and assuming no friction, calculate the total mechanical energy (kinetic + gravitational potential) of the car at this point.
An engineer designs a machine that takes in 1200 J of electrical energy and claims it produces 500 J of useful mechanical energy and 800 J of thermal energy. What conclusion can be drawn?
A 2.0 kg object is launched vertically upward with a speed of 14 m s⁻¹. Using g = 9.8 N kg⁻¹ and assuming no air resistance, determine the maximum height reached.
A battery connected to a heater warms water in a beaker. Which row correctly identifies the initial store, the final store, and the transfer pathway?