Test on Work, Energy, and Power

Question 1: The formula for calculating an object's kinetic energy is its mass multiplied by its speed squared.

A. Ano

B. Ne

Explanation: The study materials state that for an object of mass m and speed v, kinetic energy = 1/2mv^2. The formula includes multiplying by one-half, not just mass multiplied by speed squared.

Question 2: According to the provided study materials, how is electrostatic energy defined?

A. Energy stored when electric charges attract each other but are held apart.

B. Energy stored by an object because of its motion.

C. Energy stored in the chemical bonds between atoms.

D. Energy stored by objects lifted upwards against the force of gravity.

Explanation: The study materials define electrostatic energy as occurring 'If electric charges attract each other but are held apart, they store energy.'

Question 3: The useful power output of a car engine maintaining a steady speed of 30 m/s against a total frictional force of 700 N is 21 kW.

A. Ano

B. Ne

Explanation: As the speed is steady, the engine must provide a forward force of 700 N to balance the total frictional force. The useful power output can be calculated as force × speed, which is 700 N × 30 m/s = 21000 W, or 21 kW.

Question 4: According to the study materials, what is the equivalent of 1 horsepower (hp)?

A. 746 W

B. 1000 W

C. Approximately ½ kilowatt

D. 3600000 J

Explanation: The study materials state that 1 hp = 746 W and is about ½ kilowatt. 1000 W is equivalent to 1 kilowatt, not 1 horsepower. 3600000 J is the equivalent of 1 kWh, which is a unit of energy, not power.

Question 5: Tidal power schemes release polluting gases into the atmosphere during electricity generation.

A. Ano

B. Ne

Explanation: The study materials state that power schemes like tidal power have no fuel costs and give off no polluting gases.