Forces and Motion

Question 1

Explain a distance time-graph?

Answer 1

Gradient gives the speed
Straight lines mean steady speed
Flat line mean stopped
Curves mean accelerating or decelerating

Question 2

Formula for speed?

Answer 2

Distance/ time

Question 3

Formula for acceleration?

Answer 3

change in velocity/ time

Question 4

Explain a velocity-time graph?

Answer 4

Gradient means the acceleration of the object
Straight line means steady acceleration
Flat line means steady speed
Curves mean increasing or decreasing acceleration

Question 5

How do you find the distance travelled on a velocity-time graph using area?

Answer 5

The distance travelled in any time interval is equal to the area under that section of the graph

Question 6

What is the formula for final speed?

Answer 6

Final speed^2 = initial speed^2 + (2 * acceleration * distance)
v2 = u2 + (2 * a * s)

Question 7

What can forces do?

Answer 7

Act on a body to change the velocity, speed, direction and shape

Question 8

Identify all 7 forces?

Answer 8

1) Gravity/ weight
2) Reaction force
3) Electrostatic force
4) Thrust(push or pull)
5) Drag/ air resistance/ friction
6) Lift
7) Tension

Question 9

What is a vector quantity?

Answer 9

Vector quantities have size and direction:
Force, velocity, acceleration, momentum

Question 10

What is a scalar quantity?

Answer 10

Scalar quantities only have size:
Mass, temperature, time, length

Question 11

What does friction oppose?

Answer 11

Motion

Question 12

What is the formula for force?

Answer 12

Mass * acceleration

Question 13

What is the formula for weight?

Answer 13

Mass * gravitational field strength

Question 14

What makes up stopping distance?

Answer 14

Thinking distance + braking distance

Question 15

What affects the stopping distance of a vehicle?

Answer 15

1) Speed
2) Reaction time
3) Mass
4) Brake quality
5) Surface condition

Question 16

Why do falling objects reach terminal velocity?

Answer 16

1) When an object falls it has much more force accelerating it than resistance slowing it down
2) As its velocity increases, resistance builds up
3) This resistance force gradually reduces the acceleration until eventually the resistance force is equal to the accelerating force.
4) At this point the object wont be able to accelerate any more so it will reach terminal velocity

Question 17

What is Hooke’s law?

Answer 17

How that extension is proportional to force

Question 18

What happens when a spring is stretched past its elastic limit?

Answer 18

When a spring has too much force added it loses its ability to return
Once its past the elastic limit it will not return to its original length

Question 19

What is the formula for momentum?

Answer 19

Mass * velocity

Question 20

What is the relation ship with force, change in momentum and time taked?

Answer 20

Force = change in momentum/ time taken

Question 21

What is Newtons first law?

Answer 21

Forces that are balanced will have no change in velocity

Question 22

What is Newtons second law?

Answer 22

A resultant force will lead to acceleration

Question 23

What is Newtons third law?

Answer 23

If object A exerts a force on object B then object B will exert a equal and opposite force on object A

Question 24

What is the formula for a moment?

Answer 24

Force * perpendicular distance from the pivot

Question 25

What is the principle of moments?

Answer 25

If a object is balanced then:
Total clockwise moments = total anticlockwise moments
If an object isn’t balanced then:
Total clockwise moments doesn’t equal total anticlockwise moments