CP2 Flashcards
Newton’s First Law
What are the two possible outcomes if an object has a resultant force of 0 N?
1) Stays stationary.
2) Keeps moving – same speed & direction.
What equation links weight, mass and gravitational field strength?
Weight = mass x gravitational field strength
Calculate the weight of an object on Earth (10N/kg) if the mass is 1000kg
W = m x g; W = 1000 x 10; W = 10,000N
How can an object moving in a circle have different velocities but travel at the same speed?
Because it is constantly changing direction and velocity is speed in a certain direction so velocity is constantly changing
Calculating resultant forces:
- If the forces are in the same direction you need to add……………………….
- If the forces are in opposite directions you need to subtract
What equation links mass, acceleration and force
F=m x a
What can be said about the forces needed to accelerate a lorry and a car by 5m/s2?
Less force needed to accelerate the car as its mass will be less than the mass of the lorry
Define inertial mass.
The mass of an object in relation to the amount of force needed to make the object move
Describe how you could measure the acceleration of a toy car
Take the mass of the car; apply a force to it and measure how its acceleration changes – see your core practical in the Focus app
Name factors that affect the thinking distance
All factors relating to driver – tiredness, distractions (phone, children, radio), drugs, alcohol, illness
Name factors that increase braking distance and explain why
Factors relating to the car / road – worn tyres, worn brakes, road surface eg. Ice, water, gravel
What equation links mass, momentum and velocity?
Momentum = mass x velocity
What equation links change in momentum, force and time?
Force = change in momentum / time F = mv-mu / t
A 2000kg car accelerates from 10m/s to 25m/s in 10 seconds. What force is needed to produce this acceleration?
F = (2000 x 25) – (2000 x 10) / 10 F = 50000 – 20000 / 10 F = 3000N
What safety features in cars reduce the large deceleration in crashes?
1) Seat belts
2) Air bags
3) Crumple zones (front and rear)
Explain why in a collision between a footballer’s head and the ball the action-reaction forces are the same size but the effects are different.
Force pairs are always the same type of force and the same size force but the forces will act in different directions meaning the footballers head and the ball will move away in different directions to each other.
What is meant by the term conservation of momentum?
Momentum before a collision will be equal to momentum after a collision
What is the difference between action reaction forces and balanced forces?
Balanced forces act on an object. Action reaction forces act of on a pair of objects
Action reaction forces act in opposite directions and are the same size
