Work and Energy

What is the formula for gravitational potential energy?

Which type of energy transformation occurs during a bungee jump?

• Chemical to thermal energy

• Gravitational potential to kinetic energy

• Electrical to mechanical energy

• Nuclear to gravitational energy

Answer explanation

During a bungee jump, the jumper starts at a height, possessing gravitational potential energy. As they fall, this energy transforms into kinetic energy, which is the energy of motion, making 'gravitational potential to kinetic energy' the correct choice.

What is the term used to describe the amount of energy transferred to or from another object by the action of a force?

• Power

• Work

• Energy

• Force

What is the formula for work done when a force causes a displacement at an angle?

• W = F + s

• W = F/s

• W = Fs cos θ

• W = Fs sin θ

Answer explanation

The formula for work done when a force causes a displacement at an angle is W = Fs cos θ. This accounts for the component of the force that acts in the direction of the displacement, making it the correct choice.

What is the SI unit of work?

• Newton

• Joule

• Watt

• Meter

Answer explanation

The SI unit of work is the Joule, which is defined as the amount of work done when a force of one Newton moves an object one meter. Therefore, the correct answer is Joule.

What happens to the work done on an object when the force is perpendicular to the displacement?

• Maximum work is done

• No work is done

• Work is doubled

• Work is halved

Answer explanation

When the force is perpendicular to the displacement, the angle between them is 90 degrees. In this case, the work done is calculated as W = F * d * cos(θ). Since cos(90° = 0), no work is done.

What is the law of conservation of energy?

• Energy can be created and destroyed.

• Energy can be transferred or transformed but not created or destroyed.

• Energy is always lost in a closed system.

• Energy is only conserved in open systems.

Answer explanation

The law of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed. This means the total energy in a closed system remains constant.

In which type of system is the total amount of energy conserved?

• Open system

• Closed system

• Elastic system

• Dynamic system

Answer explanation

In a closed system, energy cannot enter or leave, ensuring that the total amount of energy is conserved. This distinguishes it from open systems, where energy can flow in and out.

What happens to energy in an inelastic collision?

• Energy is completely conserved.

• Energy is lost to the surrounding environment as heat and sound.

• Energy is transformed into potential energy.

• Energy is transferred without any loss.

Answer explanation

In an inelastic collision, kinetic energy is not conserved; instead, some energy is transformed into heat and sound, which are lost to the surrounding environment. Thus, the correct choice is that energy is lost to the surroundings.

What happens to momentum in an inelastic collision?

Answer explanation

In an inelastic collision, momentum is conserved overall, but kinetic energy is not. The total momentum before and after the collision remains the same, which is why the correct answer is 'same'.