P5 Forces

Question 1

What is the unit of force?

Answer 1

newton (N)

Question 2

What is a resultant force?

Answer 2

The overall force on an object.

Question 3

List four contact forces.

Answer 3

Normal contact force, friction, air resistance, tension.

Question 4

List three non contact forces.

Answer 4

Magnetism, gravity, electrostatic.

Question 5

What equation links, force, extension and spring constant?

Answer 5

Force = spring constant x extension

F = ke

Question 6

If the elastic limit is not exceeded, what does a graph of force against extension for a spring look like?

Answer 6

Straight line through the origin.

Question 7

Distance and displacement - which is a vector and which is a scalar?

Answer 7

Distance = scalar Displacement = vector

Question 8

What’s the difference between speed and velocity?

Answer 8

Speed is a scalar, velocity is a vector.

Question 9

What is the equation for speed?

Answer 9

Speed = distance/time

Question 10

How do you calculate speed from a distance-time graph?

Answer 10

Gradient of graph = speed

Question 11

What is the equation to calculate accceleration?

Answer 11

Acceleration = change in speed/time taken

Question 12

How do you calculate acceleration fom a velocity-time graph?

Answer 12

Gradient of graph = acceleration

Question 13

How can distance be calculated from a velocity- time graph?

Answer 13

Distance travelled is the area under the graph.

Question 14

If an object has balanced forces acting on it. What happens?

Answer 14

A stationary object remains stationary, a moving object continues at the the same speed in the same direction.

Question 15

What are the overall forces on an object at terminal velocity?

Answer 15

Zero, the forces are balanced.

Question 16

What equation connects mass, force and acceleration?

Answer 16

Force = mass x acceleration

Question 17

What is the elastic limit?

Answer 17

The point at which an object will no longer return to its original shape when any external forces are removed.

Question 18

What is Newton’s Third Law?

Answer 18

For every action there is an equal and opposite reaction.

Question 19

What is stopping distance?

Answer 19

Stopping distance = thinking distance + braking distance

Question 20

List the factors affecting thinking distance.

Answer 20

Speed, tiredness, alcohol/drugs, distractions (e.g. mobile phones)

Question 21

List the factors affecting braking distance.

Answer 21

Speed, brake condition, wet/icy roads, tyre condition.

Question 22

What is the main energy transfer during braking?

Answer 22

Kinetic to thermal (heat)

Question 23

What is centre of mass?

Answer 23

The point at which all of an object’s mass appears to be concentrated.

Question 24

What is the equation for calculating weight?

Answer 24

Weight = mass x gravitational field strength

Question 25

How is momentum calculated?

Answer 25

Momentum = mass x velocity

Question 26

What is conservation of momentum?

Answer 26

The total momentum before a collision = the total momentum after the collision

Question 27

Describe how the objects are moving in these distance time graphs.

Answer 27

A - stationery

B - constant speed away from start point

C - constant speed towards start point

D - accelerating

E - decelerating

F - constant speed but slower than B