Mechanics Flashcards
How does a crumple zone in a car decrease the force on the driver?
Makes the car take longer to stop, increasing the impact time and decrasing the force.
How do seat belts decrease the force on the driver?
They streatch slightly, increasing time taken for passenger to stop. This reduces the forces acting on the chest.
How do air bags in a car decrease the force on the driver?
Slow down driver more gradually and stops them hitting hard surfaces in the car.
Define Impulse
The product of force and time. Impuls on a mody is equal to the change of momentum of that body. Ns
What is an elastic collision?
is a collision where momentum is conserved and kinetic energy is conserved
What is a projectile?
A projectile has a single force that acts upon it - the force of gravity.
What is work?
When energy is transferred. Eg friction to heat
How do you find work done from a force displacment/didtance graph?
Area underneath
Why do projectiles follow a curved path?
Because the horizontal velocity remains constant while the verticle velocity is affected by the acceleration due to gravity.
Is impulse a scalar or vector
Vector
What is the rate of change of momentum of a body falling freely under gravity?
Weight
What graph is the area underneath equal to Momentum?
Force and time graph
The force acting on an object is equivilant to? (impulse)
The impulse it recives per second
What is the unit for rate of change of momentum
Kg ms -2
