Forces and motions

Question 1

what is the equation for speed

Answer 1

speed= distance /time

Question 2

what is the equation for acceleration

Answer 2

acceleration= Change in velocity/ time

Question 3

How do you carry out the investigation of motion

Answer 3

1. set a ramp up
2. You will need two/three light gates one at the start one at the end
3. mark a line on the starting point ( to make sure you start the toy car from the same point each time)
4. measure the distance between each light gate or marking ( this will be used to work out the average speed)
5. let go off the car before the the light gate so it rolls down the slope
6. the light gate should be connected to a computer, when the car passes the light gate the light beam will be broken and a time is recorded (data logging)
7. Repeat 3 times and calculate an average
8. use formula speed= distance/ time

Question 4

how do you work out the acceleration on a velocity time graph

Answer 4

find out the gradient

Question 5

How do you work out distance travelled on a velocity time graph

Answer 5

by working out the area under the graph

Question 6

what is a vector quantity

Answer 6

Has direction and magnitude

Question 7

what is a scalar quantity

Answer 7

only has magnitude

Question 8

what are examples of scalar quantities

Answer 8

examples
- Speed
-distance
-mass
-temperature

Question 9

what are examples of vector quantities

Answer 9

• velocity
  -displacement
  -acceleration
  -lift
  -drag
  -force

Question 10

what is the equation for resultant force

Answer 10

resultant force= mass x acceleration

Question 11

how do u work out resultant force across a line

Answer 11

Add forces in the same direction

minus forces in opposite directions

Question 12

what is friction

Answer 12

a force which opposes motion

Question 13

what is the equation for force

Answer 13

force= mass x acceleration

Question 14

what is the equation for weight

Answer 14

weight= mass x gravitational field strength

Question 15

how do you work out stopping distnace

Answer 15

stopping distance= thinking distance + breaking distance

Question 16

what factors effect thinking distance

Answer 16

How fast you are going

reaction time

Question 17

what factors effect reaction time

Answer 17

-alcohol
-drugs
-age
-inexperience
-tiredness

Question 18

what factors effect breaking distance

Answer 18

1. How fast you are going
2. grip
   -Friction
   - road surface
   -weather conditions
   -tyres
3. mass
4. conditions of brakes

Question 19

what does hooks law say

Answer 19

extension is proportional to force

• an object will obey hooks law if a pair of opposite forces are applied to each end

Question 20

when does hooks law stop working (Hint refer to graph)

Answer 20

• there is a limit to the force you can apply for Hooke’s law to stay true
• when the force becomes great enough the graph start to curve

-then it reaches an elastic limit

• if a force is applied after the elastic limit, the material will be permanently stretched
• some materials like rubber only obey hookes law for really small extensions

Question 21

what does the E on the hooks law graph represent

Answer 21

Elastic limit