Momentum Flashcards
What is the thinking distance?
The thinking distance is the distance travelled by the car as the driver reacts to apply the breaks.
What is the equation to work out thinking distance?
thinking distance (m) = speed of car (m/s) x reaction time (s)
What is braking distance?
Braking distance is the distance travelled by the car while the brakes are applied before the car comes to a stop.
What is the equation to work out braking distance?
stopping distance = thinking distance + braking distance
What 2 factors make the thinking distance increase?
- when the speed of the car increases
- when the driver’s reaction time increases
What 3 things can cause the driver’s reaction time to increase?
- tiredness
- distraction
- under the influence of drugs or alcohol
What 2 factors make the braking distance increase?
- when the mass of the car increases
- when the speed of the car increases
How is friction created?
When 2 surfaces slide past each other, the interaction between them produces a force of friction.
What does a moving object have?
A moving object always has a momentum.
Why is momentum a vector quantity?
Momentum is a vector quantity as it has both a force and a direction.
What is the equation to work out momentum?
momentum (kg m/s) = mass (kg) x velocity (m/s)
What 2 things has momentum got?
- magnitude
- direction
What is magnitude?
Magnitude is the amount of the object’s mass.
What does direction depend on?
Direction depends on the velocity of the object.
What is conserve momentum?
Where momentum stays the same in explosions and collisions.
What are seat belts and crumple zones designed to do?
Seat belts and crumple zones are designed to reduce the forces on the body if there is a collision.
What do seat belts do?
Seat belts stop you moving around inside the car if there is a collision. However, they are designed to stretch slightly in a collision. This increases the time taken for the body’s momentum to reach zero, so reduces the forces on it.
What do airbags do?
Air bags increase the time taken for the head’s momentum to reach zero, so reduce the forces on it. They also act a soft cushion and prevent cuts.
What is the equation for force involved in changing the momentum of an object?
force (n) = change in momentum (kg m/s) divided by time (s)
