Newtons Three Laws Of Motion Flashcards
Summarise Newtons Third Law
Whenever two object interact, they exert equal and opposite forces on each other
What type of group does a force come in
Forces always come in pairs, these are called action - reaction pairs
How does Newton’s third law work
when Object A exerts a force on Object B, Object B SIMULTANEOUSLY exerts an oppositely directed force of equal magnitude on Object A.
When do these two forces exert a force
both objects exert a force at the exact same time
What are some properties of action - reaction pairs
- They act simultaneously.
- They act on two different objects.
- They are equal in magnitude.
- They are the same type (both contact or non-contact forces).
- They act in opposite directions
How does Newtown third law apply to a lady leaning on a wall
As she leans (pushes) on the wall, the wall pushes back on her. These forces are equal but opposite in direction.
What is Newton’s third law
Newton’s Third Lawis when two objects exert forces on each other equal in magnitude but opposite in direction.
What does an object need in order to accelerate
for an object to accelerate, the resultant or net force cannot be zero and must have a value.
What is Newton’s second law of motion
When a net force is applied to an object of a certain mass, the object accelerates in the direction of the net force. The acceleration is directly proportional to the net force and inversely proportional to the mass.
What is acceleration
the rate of change of velocity with time.
What does the net force do to acceleration
The net force will cause a change in the acceleration, but not vice versa.
The larger the force, the greater the acceleration.
How is the relationship between force and acceleration directly proportional
When you compare the relationship between net force and acceleration, the mass must be kept constant. If you change the mass at the same time, it would have an effect on the acceleration.
What else can cause a change in acceleration
The mass of the object
What are some good ways to approach questions on Newtons three laws of motion
- Underline important information in the question statement. For example - constant velocity, at rest or accelerating. This tells you if it is Newton’s first or second law.
- Draw a free body of both objects even if it is not asked for as that will show you all the forces acting on the objects.
- Convert to Si units.
- Always check that you have answered the question that was asked and check that you didn’t leave out units.
