2.3 Work, Energy & Power

What is the equation for kinetic energy?

• E = mgh

• E = 1/2 kx^2

• E = 1/2 mv^2

• E = Fs

Which of the following statements about gravitational potential energy is correct?

• If a mass falls it will lose gravitational potential energy

• If a mass is lifted up it will lose gravitational potential energy

• If a mass falls it gains gravitational potential energy

• If a mass travels horizontally then gravitational potential energy is lost

Which of the following is the correct definition for elastic potential energy?

• Elastic potential energy is a measure of how much a material can be stretched or compressed

• Elastic potential energy is the maximum amount that can be stretched or compressed

• Elastic potential energy is a measure of the stiffness of a material

• Elastic potential energy is the energy stored within a material (e.g. in a spring) when it is stretched or compressed

Which feature of a force-extension graph represents the work done on a material under tensile stress?

• Gradient

• Area

• y-intercept

• x-intercept

What is a material with a high breaking stress described as?

• Strong

• Brittle

• Ductile

• Elastic

Which one of the following situations does not describe the work done on an object?

• Lifting a bar above the head

• Pushing a supermarket trolley across a car park

• Walking up stairs

• Holding a box at a height of 1.5 m above the floor

What are the correct units for power?

• Joules

• Watts

• Newton meters

• Newtons

Which row describes an energy transfer?

• Elastically

• Chemically

• Gravitational Potentially

• Electrically

What is another way of saying that energy is wasted?

• Energy has been transferred

• Energy has been dissipated

• Energy has been conserved

• Energy has been destroyed

Which is the correct equation for the efficiency of a system?

• Efficiency = useful energy in / total energy out * 100

• Efficiency = wasted energy out / total energy out * 100

• Efficiency = useful energy out / total energy in * 100

• Efficiency = energy transferred / time * 100