1.3 Dynamics

Question 1

What is a force?

Answer 1

A force on a body is a push or a pull acting on the body from some external body. It is measured in Newtons, N.

Question 2

What is newtons first law?

Answer 2

Newton’s first law states that when the resultant force is 0 N, a body will remain stationary or continue moving with a constant velocity. Therefore, unbalanced forces will cause a change in the motion of a body.

Question 3

What is newtons third law?

Answer 3

Newton’s third law states that if body A, exerts a force on body B, then B exerts an equal and opposite force on A.

Question 4

What is the equation for momentum?

Answer 4

p=mv

The momentum, p, of an object is a vector and is equal to its mass, m, multiplied by its velocity, v. It is measured in units of kg m s-1.

Question 5

What is the principle of conservation of momentum?

Answer 5

The principle of conservation of momentum states that the vector sum of the momenta of bodies in a system stays constant even if forces act between the bodies, provided there is no external resultant force.

This means that the total momentum before an interaction, e.g. a collision, is equal to the total momentum afterwards, as long as there is no external resultant force.

Question 6

What is an inelastic collision?

Answer 6

A collision where kinetic energy is lost, and transferred into other energy types

Question 7

What is an elastic collision?

Answer 7

In an elastic collision the kinetic energy before and after the collision will be equal.

Question 8

What is newtons second law? - words

Answer 8

Newton’s second law states that the rate of change of momentum of an object is proportional to the resultant force acting on it and takes place in the direction of that force.

This can be written as the following equation:

∑F = Δp/Δt = Δ(mv)/Δt