P2.2 Forces Flashcards
Name some forces [8]
- Resistance
- Push
- Pull
- Friction
- Weight
- Thrust
- Reaction force
- Up thrust
What are forces measured in?
Newtons (N)
What does the resultant force do?
Gets an object moving
What happens to the forces when there is a constant speed?
They are balanced
What is the resultant force when there is a steady speed?
Zero
What does it mean when the resultant force doesn’t equal zero?
The object is accelerating or decelerating
What is another equation for acceleration?
Acceleration = force/mass
What is the equation for resultant force?
Resultant force = forward force (thrust) - friction (drag)
What is the equation for working out stopping distance?
Stopping distance = thinking distance + braking distance
What things can affect thinking distance? [4]
- Tiredness
- Alcohol
- Reflexes
- Speed
What things can affect braking distance? [4]
- Road conditions
- Quality of brakes
- Speed
- Quality of tires
What is the equation for weight?
Weight (N) = mass (kg) x gravitational field strength (N/kg)
What is the equation for working out force?
Force = mass (kg) x acceleration
What is the equation for work done?
Work done = force x distance
What is Hooke’s law?
Extension of a spring is directly proportional to the force applied. Provided its limit of proportionality is not exceeded
What is the equation for gravitational potential energy?
Gravitational = weight (N) x Change in height (m)
potential
energy (J)
What is the equation for gravitational potential energy when you don’t know the weight?
Gravitational = mass (kg) x gravitational x change in height potential field (m) energy (J) strength (N/kg)
What is the equation for kinetic energy?
Kinetic energy = 1/2 x mass x velocity²
How do you convert grams into kilograms?
divide it by 1000
What is the equation for momentum?
Momentum (kg m/s) = mass (kg) x velocity (m/s)
Define impact forces
High shocks applied when two or more things collide over a short space of time
Define what air bags do
They slow down a change in momentum reducing the impact force
A small hole means the head pushes the air slowly breaking their fall
Define what seatbelts do
They stretch as the car suddenly stops slowing down a person’s stopping rate
Define what a crumple zone does
It crumples up on impact which absorbs the main impact of a crash
