Laws of Motion and Momentum

?
  • Created by: CPev3
  • Created on: 16-06-20 11:31

Newton's first law of motion

  • An object will remain at rest or continue to move with constant velocity unless acted upon by a resultant force

.

  • Velocity is a vector quantity, so an object's velocity changes if its speed and/ or direction changes
1 of 12

Newton's third law of motion

  • When two objects interact, they exert equal and opposite forces on each other

.

  • The forces acting on the interacting objects are always of the same type
2 of 12

The four fundamental forces

  • Gravitational
  • Electromagnetic
  • Strong nuclear
  • Weak nuclear
3 of 12

Linear momentum equation

p (momentum) = m (mass) * v (velocity)

4 of 12

Principle of conservation of momentum

For a system of interacting objects, the total momentum in a specified direction remains constant, as long as no external forces act on the system

5 of 12

Example of zero momentum

A gun recoils when a bullet is fired

.

The momentum of the gun and the momentum of the bullet have the same magnitude but act in oppsite directions

.

The total momentum of the cloesed system remains the same and is equal to zero

6 of 12

Perfectly elastic collision

  • Momentum conserved
  • Total energy conserved 
  • Total kinetic energy conserved
7 of 12

Inelastic collision

  • Momentum conserved
  • Total energy conserved
  • Total kinetic energy not conserved
8 of 12

Newton's third law of motion

  • The net force acting on an object is directly proportional to the rate of change of its momentum, and is in the same direction

.

  • F (force)Δp (change in momentum) / Δt (time)
9 of 12

Force equation

F = Δp / Δt

.

F = (mv - mu) / t

.

F = m ((v-u) / t)

.

F = ma

10 of 12

Why momentum is conserved in collisions

According to Newton's third law of motion, each object experiences an equal but opposite force

.

The net force acting on the objects in this closed system is zero

.

According to Newton's second law of motion, Δp / Δt = 0

.

The change in momentum of both objects must be zero

.

The total momentum of the objects does not change

.

Momentum is always conserved

11 of 12

Impulse of a force

  • The product of force and the time for which this force acts on an object

.

  • Change in momentum

.

  • The area under a force-time graph
12 of 12

Comments

No comments have yet been made

Similar Physics resources:

See all Physics resources »See all Forces resources »