P10 Force and motion Flashcards
How to calculate resultant force?
Resultant force, F(newtons, N)=mass, M(kilograms, kg) x acceleration, A(metres per second squared, m/s^2)
What is Newtons second law of motion?
It says the acceleration of an object is proportional to the resultant force on the object but it is inversely proportional to the mass of the object.
What is inertia?
Inertia is the tendency of an object to stay at rest or to continue in uniform motion. Inertia mass can be defined as force/acceleration.
What happens when something speeds up or slows down?
The velocity increases if the resultant force is in the same direction as the velocity but if the velocity decreases, the resultant force is in the opposite direction to its velocity.
What is weight and mass described as?
The force acting on it due to gravity and the mass depends on the quantity of matter in it.
What is the formula for weight?
Weight, W(newtons, N) = mass x gravitational field strength.
What is terminal velocity?
When the object reaches a constant velocity where the frictional force is equal and opposite to its weight so the resultant force and therefore acceleration is 0.
What does braking force depend on?
The speed of which the vehicle is travelling at and the mass of the vehicle. Therefore the greater the speed, the greater the deceleration needed to stop it within a certain distance and same with mass.
What are the two types of stopping distance and what are they?
The thinking distance-the distance for the driver needed to react
The braking distance-the distance travelled by the vehicle during the time the braking force acts.
What is the formula for stopping distance?
Stopping distance=thinking distance + braking distance
What are factors effecting stopping distances?
Tiredness, alcohol and drugs affect the brain increasing reaction time, the speed the vehicle is travelling, in adverse road conditions and poorly maintained vehicles with worn tires or brakes.
What is the formula for momentum?
momentum of a moving object=mass x velocity
What is the conservation of momentum?
In a closed system, the total momentum before an event is equal to the total momentum after the event.
What is the formula for change in velocity?
Force x time taken / mass
What happens when two things collide?
They exert equal and opposite forces on each other so their total momentum is unchanged.
