Newton’s first law of motion
Every object remains in its state of rest or in uniform motion in a straight line, unless acted on by an unbalanced force.
Newton’s second law of motion
The acceleration of an object produced by a force is directly proportional to the force, is in the same direction as the force, and is inversely proportional to the mass of the object. (F=ma)
Newton’s third law of motion
Every action has an equal and opposite reaction.
What is mass?
The amount of matter in a body, regardless of its volume or position
What is weight?
The weight of a body is the gravitational force of attraction between the mass of the Earth and the mass of a body.
What happens to the weight of a body as it moves away from the earth’s centre?
It decreases as gravitational strength depends on distance from earth’s centre
Weight formula
W = mg
What is the difference between mass and weight?
Mass is the same anywhere in the universe, whereas weight depends on the position of the body
What is work and what does it depend on?
Work is done when a force causes movement or displacement of an object. Depends on the size of the force and distance moved by the object.
What is one Joule of work equal to?
A force of one Newton causing a body to move one metre
Work formula
W = F x s
What is power and what is it measured in?
A measure of the rate at which work is done or at which energy is converted from one form to another. Measured in Watts (W)
Power formula
P = W/t
What is energy and what is it measured in?
It is the capacity to do work. Measured in Joules
Gravitational potential energy formula
GPE = mgh
Kinetic Energy formula
KE = 1/2mv2
Where is chemical energy stored?
In the chemical bonds between atoms
How can you calculate the efficiency of a machine?
Divide the useful energy output by the total energy input. Multiply by 100 for a %
Momentum formula?
Mass x Velocity
Impulse formula?
Force x time
What is impulse?
The change of momentum
Factors affecting rigidity of a spinning rotor?
Rotor mass
Radius at which the mass acts
Speed of rotation
Bearing friction
Describe the two properties of a gyroscope
Rigidity: Ability of a spinning rotor to retain its axis in a fixed direction in space unless acted on by external forces
Precession: if an external force is applied to change the direction of the rotor spin axis, the gyro resists the change and moves the force at right angles to the direction originally applied.
