topic 1 - forces and motion

Question 1

how to plot a distance time graph and how to interpret it

Answer 1

• y axis shows distance
• x axis shows time
• straight line means constant velocity
• the steeper the line, the faster the object is travelling

Question 2

relationship between average speed, time taken and distance moved

Answer 2

average speed = distance moved/time taken

v = d/t

Question 3

investigating motion independent variable

Answer 3

distance

Question 4

investigating motion dependent variable

Answer 4

time

Question 5

investigating motion control variable

Answer 5

same tennis for each measurement

Question 6

investigating motion method

Answer 6

• 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

Question 7

relationship between acceleration, change in velocity and time taken

Answer 7

acceleration = change in velocity/time taken

a = (v-u)/t

Question 8

how to plot a velocity time graph and how to interpret it

Answer 8

• 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

Question 9

what does the area under a velocity-time graph show

Answer 9

distance travelled by object

Question 10

how to find acceleration using gradient of a velocity-time graph

Answer 10

gradient = acceleration = change in velocity/change in time

Question 11

relationship between final speed, initial speed, acceleration and distance moved

Answer 11

acceleration = (final speed^2 - initial speed^2)/2 x distance moved

a = (v^2 - u^2)/2s

Question 12

effects between forces between bodies

Answer 12

change in speed, shape or direction

Question 13

9 forces

Answer 13

gravitational, weight, thrust, up thrust, friction, electrostatic, air resistance, tension, lift

Question 14

what are vectors

Answer 14

quantities with magnitude and direction

Question 15

what are scalars

Answer 15

quantities with only magnitude

Question 16

is force a vector or scalar

Answer 16

a vector as it has magnitude and direction

Question 17

how to calculate resultant force

Answer 17

object —–> 60N
—> 30N
= 90N to the right

10N <– object —–> 30N
= 20N to the right

Question 18

what is friction and what does it oppose

Answer 18

friction is caused by surfaces rubbing. the force always acts in the opposite direction to motion

Question 19

relationship between force, mass and acceleration

Answer 19

force = mass x acceleration
F = m x a

Question 20

relationship between weight, mass and gravitational field strength

Answer 20

weight = mass x gravitational field strength

W = m x g

Question 21

how to calculate stopping distance

Answer 21

thinking distance + breaking distance

Question 22

4 things affecting thinking distance

Answer 22

• alcohol
• drugs
• tiredness
• speed of car

Question 23

5 things affecting breaking distance

Answer 23

• road conditions
• tyre conditions
• brake conditions
• speed of car
• mass of car

Question 24

describe forces acting on a falling object

Answer 24

• 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.

Question 25

method for investigating how extension varies with applied force for helical springs, metal wires and rubber bands

Answer 25

1. Set up your apparatus as shown in the 2. Measure the length of your spring without any hanging masses. 3. Hang a mass of 100g on the spring 4. Measure the new length of the spring 5. Calculate the extension of the spring 6. Repeat steps 3-5 for increasing the mass in increments of 100g 7. Take note of your results in the table.

Question 26

what is Hooke's law

Answer 26

extension is directly proportional to force applied. this is shown in a straight line on a graph

Question 27

what is elastic behaviour

Answer 27

Elastic behaviour is the ability of a material to recover original shape after the force is removed.