PHYSICS - Work and Energy Flashcards
What is work done measured in?
Joules
What is the equation for gravitational potential energy (GPE) in joules?
mass x gravitational field strength x height change
(GPE = m x g x h)
What is GPE tho?
Object placed at a height above ground
What is the formula for kinetic energy?
KE = 1/2 x mass x speed
What is KE tho?
Object moving has this
How do seat belts make cars safer?
Seat belts stop you tumbling around inside the car if there is a collision. However, they are designed to stretch a bit in a collision. This increases the time taken for the body’s momentum to reach zero, and so reduces the forces on it.
How do airbags make cars safer?
Airbags increase the time taken for the head’s momentum to reach zero, and so reduce the forces on it. They also act as a soft cushion and prevent cuts.
How do crumple zones make cars safer?
Crumple zones are areas of a vehicle that are designed to crush in a controlled way in a collision. They increase the time taken to change the momentum of the driver and passengers in a crash, which reduces the force involved.
What is the formula for Hooke’s Law?
(seems more important than any other equation)
F = k x X
(F = force, k = spring constant, X = extension)
What happens when a spring’s elastic limit is exceeded?
After being stretched past the elastic limit, the spring will not return to it’s original length
What is ‘work’ the measure of?
Energy transfer
How can vehicle energy efficiency
Reducing:
• aerodynamic losses
• rolling resistance
• idling losses
