Energy and Motion- I

If two objects with different weights are moving at the same speed, the lighter object has

• less energy than the heavier object.

• more energy than the heavier object.

Answer explanation

The kinetic energy of an object is given by the formula KE = 1/2 mv², where m is mass and v is velocity. Since both objects are moving at the same speed, the lighter object (less mass) will have less kinetic energy than the heavier object.

Scientists say that energy is conserved because energy

• cannot be transferred between objects.

• cannot be created or destroyed.

Answer explanation

Energy is conserved because it cannot be created or destroyed, only transformed or transferred. This principle is fundamental in physics, ensuring that the total energy in a closed system remains constant.

What is energy?

• the speed of an object is able to move at

• the ability to make an object move or change.

Answer explanation

Energy is defined as the ability to make an object move or change, which encompasses various forms such as kinetic and potential energy. The other option refers to speed, not the broader concept of energy.

Which of the following would have the most energy?

• a fast and heavy object

• a fast and light object

Answer explanation

A fast and heavy object has more kinetic energy than a fast and light object because kinetic energy is calculated as 1/2 mv², where m is mass and v is velocity. Thus, the greater mass contributes significantly to the energy.

When a moving object stops moving, it has ____ energy.

• gained

• lost

Answer explanation

When a moving object stops, it loses kinetic energy, as energy is required to maintain motion. Therefore, the correct answer is 'lost'.

An object with potential energy

• has the baility to move

• has lost all of its energy

Answer explanation

An object with potential energy has the ability to move because it is stored energy that can be converted into kinetic energy, allowing the object to perform work or move when released.

____ is an example of an object with stored energy only.

• A ball bouncing

• A person standing up

Answer explanation

A person standing up has potential energy due to their position, while a ball bouncing involves kinetic energy in motion. Thus, the correct answer is a person standing up, as it represents stored energy only.

When you throw a rock, you are ___ energy.

• storing

• transferring

Answer explanation

When you throw a rock, you are transferring energy from your body to the rock, causing it to move. This process involves the conversion of kinetic energy, making 'transferring' the correct choice.

Two factors that affect an object's energy are

• weight and speed

• moving and transferrring

Answer explanation

Weight and speed are crucial factors affecting an object's energy. Weight influences gravitational potential energy, while speed affects kinetic energy. Thus, the correct answer is weight and speed.

Stored energy is also known as

• potential energy

• kinetic energy

Answer explanation

Stored energy is referred to as potential energy, which is the energy held by an object due to its position or state. Kinetic energy, on the other hand, is the energy of motion.