Calculating the energy of a moving object (KE=1/2mv2) | Starter Quiz | Oak National Academy

Which properties of an object can be increased so it has more energy in its kinetic store?

• height

• mass

• speed

• temperature

Answer explanation

Increasing the mass or speed of a moving object means that there is more energy in the kinetic store.

Why does a shopping trolley that has been pushed and then let go of come to a stop?

• it runs out of energy

• energy is transferred to the surroundings

• a gravitational force pushes down on it

Answer explanation

Friction and air resistance push backwards on the trolley to slow it down and energy is transferred to the surroundings by heating and by making air particles move more quickly.

What happens to the amount of work done moving a car, if the car is pushed with the same size force for three times the distance?

• One third of the work.

• The same amount of work.

• Three times the work.

• Nine times the work.

Answer explanation

The car is pushed three times as far so will require three times as much energy to be transferred.

In which of these situations does the applied force not do any work?

• Pushing a trolley forward to speed it up.

• Pushing a trolley forward against friction, to keep it at the same speed.

• Pushing down on a trolley as it moves forwards.

• Pushing on a trolley backwards to slow it down.

Answer explanation

Pushing down on a trolley does not make it move, so no work is done.

How would you calculate the work done by a catapult in shooting a small ball forward?

• Work done = force of catapult × distance over which it pushes on the ball

• Work done = force of catapult ÷ distance over which the ball moves

• Work done = force of catapult × mass of the ball

• Work done = force of catapult ÷ mass of the ball

Answer explanation

Work is done by the catapult when it is pushing on the ball and making it move forward. Work done = force × distance moved in the direction of the force.

A catapult does work on a small ball to fire it vertically up into the air. What is the amount of work done on the ball equal to?

• Energy in the kinetic store as the ball leaves the catapult.

• Energy in the kinetic store at its highest point.

• The energy in the gravitational store when the ball leaves the catapult.

• Energy in the gravitational store at its highest point.

Answer explanation

As the ball leaves the catapult, the energy in the kinetic store is equal to the work done on the ball. As it moves through the air, energy is dissipated to the surroundings and energy of the ball becomes less.