Energy and Power Concepts for Grade 8

What is the formula for calculating kinetic energy?

• KE = 1/2 m * v

• KE = 0.5 * m * v²

• KE = m * v^2 / 2

• KE = m * v

If a 2 kg object is moving at 3 m/s, what is its kinetic energy?

• 6 Joules

• 12 Joules

• 3 Joules

• 9 Joules

How does potential energy change when an object is lifted?

• Potential energy is irrelevant to the height of an object.

• Potential energy increases when an object is lifted.

• Potential energy remains constant when an object is lifted.

• Potential energy decreases when an object is lifted.

What is the unit of measurement for electricity consumption?

• J/s

• kilowatt-hours (kWh)

• J

• kg m²/s²

If a light bulb uses 60 watts of power for 5 hours, how much energy does it consume?

• 300 watt-hours

• 600 watt-hours

• 150 watt-hours

• 120 watt-hours

Define power in terms of energy and time.

• Power = Energy + Time

• Power = Energy - Time

• Power = Time / Energy

• Power = Energy / Time

If a machine does 200 joules of work in 10 seconds, what is its power output?

• 50 watts

• 20 watts

• 25 watts

• 15 watts

What is the potential energy of a 5 kg object at a height of 10 meters?

• 50 Joules

• 1000 Joules

• 490.5 Joules

• 245 Joules

How do you calculate the total mechanical energy of a system?

• Total Mechanical Energy (TME) = KE x PE

• Total Mechanical Energy (TME) = KE + 2PE

• Total Mechanical Energy (TME) = KE + PE

• Total Mechanical Energy (TME) = PE - KE

What happens to kinetic energy when an object comes to a stop?

• Kinetic energy increases significantly.

• Kinetic energy becomes zero.

• Kinetic energy is transferred to another object.

• Kinetic energy is converted to potential energy.