Linear Motion and suvat equations

Question 1

What do all the letters in suvat stand for?

Answer 1

s = displacement (m)
u = inital velocity (ms^-1)
v = final velocity (ms^-1)
a = accleration (ms^-2)
t = time (s)

Question 2

When do you use suvat?

Answer 2

When there is constant acceleration.

Question 3

How do we derive the suvat equations?

Answer 3

Using the Equations of motion graph.

Question 4

Sketch the equation of motion graph?

Answer 4

Look at notes!

Question 5

A mug is dropped from 2.0m. How long does it take to hit the ground and how fast does it hit the ground?

Answer 5

t = 0.639s.
v = 6.26ms^-1.

Question 6

What value is g?

Answer 6

9.81ms^-2.

Question 7

What does stopping distance equal?

Answer 7

Thinking distance + Braking distance.

Question 8

What depends on someone’s thinking distance? (5)

Answer 8

1) The speed you are traveling
2) tiredness
3) Drugs
4) Alcohol
5) Distractions

Question 9

What depends on someone’s braking distance? (4)

Answer 9

1) Their speed
2) The condition of their brakes
3) The condition of their tires
4) The road surface

Question 10

What is reaction time directly proportional to?

Answer 10

The distance traveled.

Question 11

What is the distance traveled proportional to?

Answer 11

The (initial speed)^2.

Question 12

How is the distance traveled directly proportional to (initial speed)^2? (3)

Answer 12

1) Due to W=fx
2) Ek = 1/2mu^2
3) fx = 1/2mu^2

Question 13

The smaller the reaction time the smaller the………

Answer 13

Thinking distance.

Question 14

What should you remember when calculating the braking distance from a speed-time graph?

Answer 14

You are calculating the area under the graph from the point when the brakes are applied.

Question 15

Describe a practicle to determine g. (3)

Answer 15

1) Set up the experiment with three clamp stand and one tripod as shown in the diagram with an electromagnet placed at the top connected to the metal ball. You should have an upper light gate and the lower light gate which are connected to a stopwatch.
2) When the electromagnet is turned off, the metal ball becomes detached from the electromagnet and accelerates through the top light gate and starts the timer then the timer is stopped as it passer throughout the lower light gate. Remember to have soft padding at the bottom to prevent damage to the object or table.
3) Plot a graph of 2s against t graph where you should expect a straight line with the gradient being equal to a.

Question 16

What has to be kept constant during the practice for determining g?

Answer 16

The distance between the object on the electromagnet to the upper light gate.

Question 17

Draw a diagram for the practice to determine g.

Answer 17

Look at notes.

Question 18

How do you know 2s/t = a = gradient?

Answer 18

Because:
1) s=ut+1/2at^2
2) 2s=2ut+at^2
3) 2s/t=2u+at
      y   =c +mx

Question 19

What is the acceleration independent of?

Answer 19

The mass of the object.

Question 20

Why is the coins maimum height, when flipped into the air, zero?

Answer 20

Because for a fraction of a second the coin stops moving to then fall back down.

Question 21

Define thinking distance.

Answer 21

Distance travelled between when the driver sees a problem and the time at which the brakes are applied.Thinking distance = speed x reaction time. Where reaction time is dependent on tiredness, alcohol or drug use, illness and distractions.

Question 22

Define braking distance.

Answer 22

The distance travelled from when a driver applies the brakes until the vehicle stops. It is affected by the road conditions and the quality/wear of the tyres.

Question 23

Define stopping distance.

Answer 23

The distance travelled from the driver seeing a problem to the vehicle coming to a complete stop.Stopping distance = Thinking distance + Braking distance.

Question 24

Define reaction time.

Answer 24

The time taken between a driver seeing a problem and reacting to the problem (i.e. applying the brakes).

Question 25

What is thinking distance directly proportional to?

Answer 25

The inital speed.

Question 26

What is braking distance directly proportional to?

Answer 26

The (speed)^2.