Forces and Motion Flashcards
Acceleration equation?
Acceleration = change in velocity/ time take A = (v-u)/ t
Average speed equation?
Average speed = distance moved/ time taken
What are forces?
Forces are pushes or pulls that one body exerts on another
What can forces do?
Forces can change the way things are moving, make things start to move or stop moving, and change the shape of things
What is weight?
The force that acts on a body because of gravity
What is friction?
The force that opposes motion (acts in opposite direction), either when you try to make something move or whilst it is moving
What is air resistance (drag)?
(A force). Friction between an object and the air (or gas) it is moving through
What is viscous drag?
(A force). Similar to air resistance, but occurs when an object is moving through a liquid
What is upthrust?
The upward force that liquid and gases exert on objects
What are magnetic forces?
Forces that magnets exert on other magnets or things made of iron (or other ferrous materials)
What are electrostatic forces?
The force between electrically charged objects
What is a vector quantity?
Both size and direction are important, examples: displacement (s), velocity (v) and force
What is displacement?
(s) distance travelled in a specified quantity
What is velocity?
(v) speed in a specified direction
What is a scalar quantity?
Just size, no need to take direction into account, examples: speed, distance, mass, energy
What happens to resultant forces acting on a line in the same direction?
They add
What happens to resultant forces acting on a line in opposite directions?
They subtract
Unbalanced force equation?
Unbalanced force = mass x acceleration
F = m x a
Weight equation?
Weight = mass x g W = m x g
Why do falling objects reach a terminal velocity?
The size of the drag force caused by air resistance increases with speed - at some speed the size of the drag force will be enough to balance the weight of the object. So the overall resultant force on the object will be zero so that it no longer accelerates, having reached its maximum or terminal velocity.
What factors affect vehicle stopping distance?
Speed, mass, road conditions and reaction time
Momentum equation?
Momentum = mass x velocity, momentum = mv
Force equation?
Change in momentum/ time taken
