A vector quantity, as it’s a product of a scalar (mass) and vector (velocity)
Define Newtons First Law
An object will continue at rest or move with constantvelocity unless a resultantforce acts upon it
How does an objects velocity change?
If its speed or direction changes
Define Newton’s third law of motion
When two objects interact, they exert equal and opposite forces on each other
What are the four fundamental forces that explain all interactions?
Gravitational, electromagnetic, strong nuclear and weak nuclear.
Explain what force is present when clapping your hands
The contact that you feel is due to the electrostatic repulsive forces between the electron clouds around the atomic nuclei in your hands
What forces are present when you walk?
You are exerting a backward force on the ground, and the ground is exerting a forward force on you.
What is the acceleration due to free fall?
9.81 ms-2
What is the principle of conservation of momentum?
When two objects interact/collide, the total momentum in a specified direction doesn’t change, provided that there are no external forces acting upon it.
What two quantities are conserved in all collisions
Momentum and total energy
What happens to the kinetic energy of objects when they collide?
Kinetic energy is not conserved, it could be retained by the objects or can be transferred to other stores, like thermal store.
Describe a perfectly elastic collision
A collision where momentum, total energy and total kinetic energy is conserved.
Describe an inelastic collision
A collision where momentum and total energy is conserved, but the total kinetic energy is not.
Define Newtons Second Law
The resultant force acting on an object is directly proportional to the rate of change of its momentum.
What is the equation for Newtons Second Law?
Force = (change in momentum) divided by (change in time)
Why is the constant ‘k’ not included in the equation for Newton’s Second Law?
The value of k is equal to 1 by defining the Newton as the force required to give a 1kg mass an acceleration of 1ms-2
When can we apply the equation F=ma?
This equation is only applicable when the mass of an object stays constant during the period of acceleration.
Define impulse
The impulse of a force is the product of force and the time for which this force acts on an object. So therefore, the impulse of a force is the change in momentum
What are the units for impulse
Ns or kgms-1
How do you work out impulse from a force-time graph?