Chapter 7- Kinetic Energy and Work

little jerk

If an object is attached to a string and given a(n) ________, its work done can not be calculated by the equation (W= Fd cos theta) because there is no one value of F to put into that equation- the value of F increases as the block stretches the spring.

net change

Therefore, the ________ in kinetic energy of the object is the sum of the work done by both the forces (since the work by gravitational energy is negative, it is actually subtracted)

Power

The rate at which work is done by an applied force.

Energy

The quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light.

Net work can be calculated in two ways

either the work done by all the forces is calculated individually and then summed up together, or the net (resultant) force is calculated and used in the formula

Principle of conservation of energy

It states that energy cannot be made or destroyed, but only changed from one form to another.

Kinetic energy

The mechanical energy that a body has by virtue of its motion.

Hooke's Law

The principle that the stress applied to a solid is proportional to the strain produced.

Work

The the energy transferred to or from an object via the application of force along a displacement.

Spring force

The force exerted by a compressed or stretched spring upon any object that is attached to it.

Variable force

The force whose direction and amplitude vary during the body's motion and is not constant, e.g. spring force.

Work-kinetic energy theorem

It states that the net work done by the forces on an object equals the change in its kinetic energy.

Gravitational Force

The force of attraction between all masses in the universe; especially the attraction of the earth's mass for bodies near its surface.