Work Power Energy

What is the definition of work in physics?

Work is the displacement of an object in a parallel direction to an applied force.

What is the definition of energy?

Energy is the ability to do work.

What is power in terms of work?

Power is the rate of doing work.

What is the relationship between work and energy?

Work is the transfer of energy.

When is work accomplished on a mass?

Work is accomplished when a force is parallel to the displacement of an object.

When is work considered positive?

Work is positive when force and displacement are in the same direction.

When is work considered negative?

Work is negative when force and displacement are in opposite directions.

How much work is done by gravity on a box resting on a shelf?

Zero, because there is no displacement.

What happens when work is accomplished on a mass?

Energy is transferred.

What happens when net work is zero while lifting a mass at constant velocity?

The potential energy increases.

What happens to kinetic energy of a mass when positive work is done by pushing it horizontally?

The kinetic energy of the mass increases.

How much work is done on a bowling ball traveling along a 19 m level alleyway due to gravity?

Zero, because the displacement is perpendicular to the gravitational force.

How much work is done while carrying a 15 kg object along a level surface?

Zero, because the displacement is perpendicular to the gravitational force.

Who accomplishes more work: Person A or Person B carrying the same box? Why?

Same amount of work because the displacements are the same.

Who generates more power: Person A or Person B? Why?

Person A generates more power because they accomplish the task in less time.

By what factor does kinetic energy increase when the speed of an object is tripled?

The kinetic energy increases nine times the original kinetic energy.

How much work is done by gravity on a satellite in circular motion around a planet?

None, because the gravitational force does not cause displacement in a parallel direction.

What is the definition of kinetic energy?

Kinetic energy is a mass’s ability to do work based on its motion.

What does the work-energy theorem state?

The work accomplished on a mass changes its kinetic energy by the same amount.

How much work is accomplished on a 65 kg mass that has a change of kinetic energy of 320 J?

320 J.

What is the definition of potential energy?

Potential energy is the amount of capable work a mass can accomplish based on its height above a reference.

What is mechanical energy?

Mechanical energy is the sum of potential and kinetic energies.

What does the conservation of mechanical energy state?

Mechanical energy remains constant in the absence of non-conservative forces.

Express the conservation of mechanical energy in equation form.

ME 1 = ME 2, PE 1 + KE 1 = PE 2 + KE 2.