Newton’s 1st law
When resultant force is 0, the object does not accelerate or decelerate. If it is already moving and the forces are balanced, it has constant velocity and does not change in speed or direction.
Newton’s 2nd law
The acceleration of an abject is directly proportional to its resultant force (F=ma). When resultant force is not 0, the object is always accelerating or decelerating
Newton’s 3rd law
For every action (force) there is an EQUAL and OPPOSITE force which MUST be same size, direction, type of force and act on different objects.
What is centre of gravity?
The point from which the weight of a body will act
Why is gravitational field strength on the moon different than on Earth?
Because the moon has a smaller mass therefore the weight is smaller and their gravity is less
Formula for weight
Weight = mass x gravitational field strength
2 suvat equations
V= u+at
V^2= U^2+ 2as
What is thinking distance
The distance you travel whilst reacting to hazard
What is a braking distance
The distance you travel whilst the pedal is being applied
Formula linking thinking distance, braking distance and stopping distance
Thinking distance+ braking distance= stopping distance
What does the gradient represent on a Distance-Time vs. a Velocity-Time graph?
Distance-Time: Gradient = Speed. Velocity-Time: Gradient = Acceleration.
How do you find the distance travelled from a Velocity-Time graph?
How do you find the distance travelled from a Velocity-Time graph?
Difference between scalar and vector quantities
Scalar- only magnitude (size)
Vector- magnitude and direction
Why does a falling object reach a steady speed?
Initially, weight > air resistance (accelerates). As speed increases, air resistance increases until it equals the weight. Resultant force is zero, so velocity is constant.
What is the relationship between force and extension?
Extension is directly proportional to force, provided the elastic limit is not exceeded. F= ke
State the Principle of Moments.
For an object in equilibrium, the sum of clockwise moments = sum of anticlockwise moments.
Formula for acceleration
A= (v-u)/t (change in rate of velocity)
Three things a force can change about an object
Speed, direction, shape
In which direction does friction always act?
Opposite direction to the motion
Factors affecting thinking distance
Increase - Fatigue, alcohol, faster speed, distractions
Decrease- slower speed, caffeine
Factors affecting braking distance
Increase - icy roads, worn tyres, driving faster
Decrease- driving slower, fresh tyres
How to measure extension of a spring?
New length- original length
Define elastic behaviour
The ability of a material to recover to its original shape after force is removed.
Formula for moment
Moment = force x (perpendicular) distance from pivot
