5 - WORK AND ENERGY

Question 1

kinetic energy

Answer 1

The energy possessed by a body by virtue of its motion

Question 2

If a body has a mass m and a speed of v, then its translational kinetic energy

Answer 2

Ek = mv /2.

Question 3

An importantresult regarding work and kinetic energy is that the work, Wi, of the resultant external force on a body is equal to the change in its kinetic energy:

Question 4

gravitational potential energy

Answer 4

the energy possessed by a body by virtue of its positions

Question 5

A body of mass m at a height h above a reference level has a gravitational potential energy of mgh with respect to that level. If a body at elevation h1 is moved to elevation h2 along any path, then the work of the gravitational force, ________. This path-independent work depends only on the body’s __________ and _________

Answer 5

Wgrav = mg(h2-h1)
initial and final elevations.

Question 6

The sum of the kinetic energy and potential energy of a body is called its total

Answer 6

mechanical energy, Em

Question 7

If a body moves from point 1 to point 2, then _________ where Wis the sum of the works done by external forces, except the gravitational force, acting on the body. If the only external force acting on the body is the gravitational force, then ________. Under this condition, the total mechanical energy of the body is said to be _______.

Answer 7

W’ = Em2 - Em1
Em1 = Em2
conserved