Newton’s First Law
- a moving object will continue to move at the same speed and direction unless an external force acts on it
- a stationary object will remain the same at rest unless an external force acts on it
Centripetal force is…
the force that acts towards the centre of the circle
Formula for weight
Weight(N) = mass(kg) x gravitational field strength(N/kg)
Newton’s Second Law
The acceleration in the direction of a resutant force depends on:
- the size of the force(for the same mass, the bigger the force the bigger the acceleration)
- the mass of the object(for the same force, the more massive the object the samller the acceleration)
Formula for Force
Force(N) = mass(kg) x acceleration(m/s²)
Newton’s Third Law
Action-reaction forces is a pair of forces that acts on two interactive objects. The two forces are always the same size and in opposite directions.
Balanced forces vs Action-Reaction forces
- Action-reaction forces act on different objects
- Balanced forces act on the same object
Momentum is…
a measure of how hard it is to stop moving
Formula for Momentum
Momentum(kg m/s) = mass(kg) x velocity(m/s)
p = mv
2 formulas for Force
1) Force(N) = acceleration(m/s²) x mass(kg)
F=ma
2) Force(N) = mass(kg) x change in velocity(m/s)/time
F=(mv-mu)/time
When moving objects collide the total momentum of both objects is…
the same before the collision as it is after the collision, as long as there no external forces.
Formula for Stopping Distance
Stopping distance = thinking distance + braking distance
Work done is…
the energy transferred by a force acting over a distance
Formula for Work Done
Work Done(J) = Force(N) x distance moved in the direction of the force(m)
Kinetic energy is…
the energy stored in a moving object
Formula for Kinetic Energy
Kinetic Energy(J) = 1/2 x mass x (speed)² KE = 1/2m(v)²
