Motion Flashcards
Newton’s first law
Moving object will move at the same speed until an external force acts upon it
Stationary object will not move until an external force acts upon it
Centripetal force
Resultant force that causes object to change direction even though it speed is the same
3 stages of forces on skydiver
Air resistance increases with speed so she is accelerating fast
Air resistance is larger but weight is the same so she is still accelerating but not as much
She is moving so fast that air resistance balances her weight and she falls at the same speed
Newton’s second law
The factors of acceleration
Size - same mass,bigger force = bigger acceleration
Mass - same force, larger mass=smaller acceleration
Force needed to accelerate an object equation
F=m x a
Inertial mass equation
Force on it / acceleration
Core practical to investigate Newton’s second law
Wood trolley with card to add height goes down a ramp with two light gates to record speed
And the time taken
Then work out the acceleration in different conditions eg more mass more force
Newton’s third law
Dog and rope
About the interaction between two different objects
Pair of same type of force and same size but different directions
Dog pulls on rope. Rope pulls on dog. Force of gravity on ground. Force of ground on dog.
Collisions and third law
Action reaction force will be the same size but different effects as objects may not be the same mass
Momentum is and scalar or vector why
The measure of the tendency for an object to keep moving
Vector because it involves velocity
Resultant force using momentum and acceleration equation
MV-MU divides by time taken (acceleration equation)
Work done equation and definition
The energy transferred by a force acting over distance
Work done = force x distance object moved
J. =. N. X. M
Crumple zones
Car hits something. Crumpling takes time. Therefore deceleration on car is less so is the force on it and it’s passengers. Because crumple zone absorbs it in the time it takes.
