Physics Chapter 6

Question 1

State Newton’s universal law of gravitation

Answer 1

The gravitational attraction between two POINT masses is directly proportional to the product of the two point masses, and inversely proportional to the square of the distance between the two point masses.

Question 2

A vehicle is moving over a circular path. In terms of forces, when does the car lose contact with the ground? (Consider the free body diagram of the car)

Answer 2

The net force acting on the car is: mg - R = mv^2/r
Where mg is the weight, R is normal reaction
As the speed of the car increases, the needed force increases, and so R decreases.
When R is 0, the car loses contact with the ground.

Question 3

Are objects moving in circular motion accelerating? (Is their velocity changing?)

Answer 3

As their velocity is changing direction, the objects are accelerating, although they are moving at constant speed.