Mechanics - Motion Flashcards
Define speed
The distance an object travels over a given time
What is the formula for speed?
v = d/t
What units is speed calculated in?
ms-1
Define acceleration
The change in speed of an object in a given time
What is the formula for acceleration?
a = change in velocity/change in time
What units is acceleration calculated in?
ms-2
In a distance-time graph, what trend represents constant speed?
diagonal line
In a distance-time graph, what trend represents acceleration?
curve sloping upwards
In a distance-time graph, what trend represents stationary?
horizontal line
In a distance-time graph, what trend represents deceleration?
upwards line curving off
In a speed-time graph, what trend represents stationary?
horizontal line along with bottom of the graph in line with 0 on the y axis
In a speed-time graph, what trend represents constant speed?
horizontal line that does not line up with 0ms-1 on the y axis
In a speed-time graph, what trend represents acceleration?
diagonal line heading upwards
In a speed-time graph, what trend represents deceleration?
diagonal line heading downwards
By calculating the slope of the line on a distance-time graph, what type of motion are you trying to find out?
constant speed
By calculating the slope of the line on a speed-time graph, what type of motion are you trying to find out?
acceleration
How do you work out the slope of a line on either graph?
vertical rise/horizontal run
How do you calculate the total speed covered on a speed-time graph?
Work out the area under the line.
If it is a rectangle, use the formula d=bxh (d = distance in metres)
If it is a triangle, use the formula d = 1/2 x b xh
Name the four forces acting on an object
Upwards = support
Downwards = weight
In the direction of movement = thrust
Against the direction of movement = friction/drag
What is the net force?
The difference in size between two opposite forces
How do you calculate net force?
F=ma
Discuss the net force acting on an object that is stationary
The opposite forces are balanced because the object is not moving therefore there is no net force acting on the object
Discuss the net force acting on an object that is moving at constant speed
The opposite forces are balanced because the object is moving at constant speed therefore there is no net force acting on the object
Discuss the net force acting on an object that is accelerating
The opposite forces are unbalanced. Thrust is greater than friction because the object is accelerating. Therefore there is a net force acting IN the direction the object is moving
Discuss the net force acting on an object that is decelerating
The opposite forces are unbalanced. Friction is greater than thrust because the object is decelerating. Therefore there is a net force acting AGAINST the direction the object is moving
How do you calculate weight force?
F = ma (acceleration due to gravity is 10ms-1)
When an object is falling straight down, what two forces are acting on the object?
Weight force and friction
When an object is falling and the weight force pulling them down is equal to the friction/drag force slowing them down, what do we call this?
Terminal velocity
When you open a parachute, explain why the friction force increases?
A parachute has a large surface area and therefore more air particles will collide with parachute which increase friction/drag
