topic 1 - forces and motion Flashcards
how to plot a distance time graph and how to interpret it
- y axis shows distance
- x axis shows time
- straight line means constant velocity
- the steeper the line, the faster the object is travelling
relationship between average speed, time taken and distance moved
average speed = distance moved/time taken
v = d/t
investigating motion independent variable
distance
investigating motion dependent variable
time
investigating motion control variable
same tennis for each measurement
investigating motion method
- measure height of 1m using metre ruler
- drop tennis ball from this height
- use stopwatch to time how long it takes to reach the bottom
- record distance (1m) and time taken
- repeat steps 2-3 and take an average
- repeat steps 1-4 for heights 1.2, 1.4, 1.6 and 1.8
relationship between acceleration, change in velocity and time taken
acceleration = change in velocity/time taken
a = (v-u)/t
how to plot a velocity time graph and how to interpret it
- velocity on y axis
- time on x axis
- straight line shows constant acceleration or deceleration
- gentle slope means small acceleration
- positive gradient shows increasing velocity
- negative gradient shows decreasing velocity
- flat line means acceleration is 0 - its moving at a constant velocity
- acceleration = gradient
what does the area under a velocity-time graph show
distance travelled by object
how to find acceleration using gradient of a velocity-time graph
gradient = acceleration = change in velocity/change in time
relationship between final speed, initial speed, acceleration and distance moved
acceleration = (final speed^2 - initial speed^2)/2 x distance moved
a = (v^2 - u^2)/2s
effects between forces between bodies
change in speed, shape or direction
9 forces
gravitational, weight, thrust, up thrust, friction, electrostatic, air resistance, tension, lift
what are vectors
quantities with magnitude and direction
what are scalars
quantities with only magnitude
is force a vector or scalar
a vector as it has magnitude and direction
how to calculate resultant force
object —–> 60N
—> 30N
= 90N to the right
10N <– object —–> 30N
= 20N to the right
what is friction and what does it oppose
friction is caused by surfaces rubbing. the force always acts in the opposite direction to motion
relationship between force, mass and acceleration
force = mass x acceleration
F = m x a
relationship between weight, mass and gravitational field strength
weight = mass x gravitational field strength
W = m x g
how to calculate stopping distance
thinking distance + breaking distance
4 things affecting thinking distance
- alcohol
- drugs
- tiredness
- speed of car
5 things affecting breaking distance
- road conditions
- tyre conditions
- brake conditions
- speed of car
- mass of car
describe forces acting on a falling object
- Initially the only force is weight as drag is proportional to velocity, so the object accelerates downwards.
- As it accelerates the velocity increases so the drag increases as well, meaning there is a smaller resultant force downwards so a smaller acceleration.
- eventually the object reaches a speed where the drag is equal to the weight meaning there is no acceleration, this velocity is know as terminal velocity.
method for investigating how extension varies with applied force for helical springs, metal wires and rubber bands
- Set up your apparatus as shown in the
- Measure the length of your spring without
any hanging masses. - Hang a mass of 100g on the spring
- Measure the new length of the spring
- Calculate the extension of the spring
- Repeat steps 3-5 for increasing the mass
in increments of 100g - Take note of your results in the table.
what is Hooke’s law
extension is directly proportional to force applied. this is shown in a straight line on a graph
what is elastic behaviour
Elastic behaviour is the ability of a material to recover original shape after the force is removed.
