Energy Unit 2 Review

What is conservation of energy in a system?

• Energy cannot be created, but it can be destroyed within a system.

• Energy is neither created nor destroyed within a system.

• Energy can be both created and destroyed within a system.

Answer explanation

The correct choice states that energy is neither created nor destroyed within a system, which aligns with the law of conservation of energy. This principle asserts that the total energy in a closed system remains constant.

Identify the type of potential energy each item can store.

• Spring: Elastic Potential Energy,

  Food: Chemical Potential Energy

• Spring: Chemical Potential Energy, Food: Elastic Potential Energy

• Spring: Thermal Energy,

  Food: Kinetic Energy

• Spring: Kinetic Energy, Food: Thermal Energy

Answer explanation

The spring stores elastic potential energy due to its ability to be compressed or stretched, while food contains chemical potential energy stored in its molecular bonds, which can be released during digestion.

Which statement is true about potential and kinetic energy of the cart on the roller coaster?

• There is more potential energy than kinetic energy.

• There is more kinetic energy than potential energy.

• There is less potential energy than kinetic energy.

• Potential and kinetic energy are always equal.

Answer explanation

At the highest points of a roller coaster, the cart has maximum potential energy due to its height. As it descends, potential energy converts to kinetic energy, but at the peak, potential energy exceeds kinetic energy.

Which of the following is a characteristic of potential energy?

• It is energy in motion.

• It is stored energy.

• It is always greater than kinetic energy.

• It cannot be converted to other forms.

Answer explanation

The correct choice is 'It is stored energy.' Potential energy refers to energy that is stored in an object due to its position or state, unlike kinetic energy, which is energy in motion.

What happens to potential energy when an object is lifted higher?

• It decreases.

• It remains the same.

• It increases.

• It converts to kinetic energy.

Answer explanation

When an object is lifted higher, its potential energy increases due to the work done against gravity. This is because potential energy is directly related to height; the higher the object, the more potential energy it has.

What is the main difference between potential and kinetic energy?

• Potential energy is always visible.

• Kinetic energy is stored energy.

• Potential energy is stored energy, while kinetic energy is energy in motion.

• Kinetic energy cannot be measured.

Answer explanation

The correct choice states that potential energy is stored energy, while kinetic energy is energy in motion. This clearly distinguishes the two types of energy, highlighting their fundamental differences.

How does kinetic energy change as an object speeds up?

• It decreases.

• It remains constant.

• It increases.

• It converts to potential energy.

Answer explanation

As an object speeds up, its kinetic energy increases because kinetic energy is directly proportional to the square of its velocity (KE = 1/2 mv²). Therefore, the correct answer is that kinetic energy increases.

What type of energy is present in a stationary object at the top of a hill?

• Kinetic energy

• Gravitational Potential energy

• Elastic Potential energy

• Electrical energy

Answer explanation

A stationary object at the top of a hill has gravitational potential energy due to its height above the ground. This energy is related to the object's position in a gravitational field, unlike kinetic or other forms of energy.

What type of energy transformation takes place in a battery-powered flashlight when turned on?

• chemical → electrical → light

• electrical → mechanical

• thermal → electrical → light

• chemical → thermal

Answer explanation

In a battery-powered flashlight, chemical energy from the battery is converted into electrical energy, which then powers the bulb to produce light. Thus, the correct transformation is chemical → electrical → light.

Which of the following terms correctly identifies the type of wave that transfers energy parallel to the motion of the medium?

• Transport waves

• Seismic waves

• Longitudinal waves

• Transverse waves

Answer explanation

Longitudinal waves transfer energy parallel to the motion of the medium, as seen in sound waves. In contrast, transverse waves move perpendicular to the medium's motion. Therefore, the correct answer is longitudinal waves.