P5-Forces

Question 1

What do vectors have?

Answer 1

Magnitude and direction.

Question 2

What quantity is force?

Answer 2

A vector quantity.

Question 3

What are lots of physical quantities?

Answer 3

Vector quantities.

Question 4

Give examples of vector quantities?

Answer 4

Force, velocity, displacement, acceleration, momentum, etc.

Question 5

Describe scalar quantities?

Answer 5

Only have magnitude and no direction.

Question 6

What are examples of scalar quantities?

Answer 6

Speed, distance, mass, temperature, time, etc.

Question 7

How are vectors normally represented?

Answer 7

An arrow showing the length of its magnitude.

And the direction showing the direction of the quantity.

Question 8

What is a force?

Answer 8

A push or pull on an object that is caused by it interacting with something.

Question 9

What is a contact force?

Answer 9

When two objects have to be touching for a force to act.

Question 10

Give examples of contact friction?

Answer 10

Friction, air resistance, tension in ropes, normal contact force, etc.

Question 11

What is a non-contact force?

Answer 11

If the objects do not need to be touching for the force to act.

Question 12

Give examples of non-contact forces?

Answer 12

Magnetic forces, gravitational force, electrostatic force.

Question 13

What is gravitational force?

Answer 13

The force of attraction between masses.

Question 14

What is the difference between mass and weight?

Answer 14

Mass is just the amount of ‘stuff’ in an object. Where as weight is the force acting on an object due to gravity.

Question 15

Why does gravitational field strength vary?

Answer 15

Because of the location. It’s stronger the closer you are to the mass causing the field, and stronger for larger masses.

Question 16

What does the weight of an object depend on?

Answer 16

The strength of the gravitational field at a location of the object. Meaning the weight of an object changes with its location.

Question 17

What is a resultant force?

Answer 17

The overall force on a point or object.

Question 18

What happens when a force moves an object through a distance?

Answer 18

Energy is transferred and work is done on the object.

Question 19

What is the conversion for joules to newton metres?

Answer 19

1J = 1Nm

Question 20

How do you use scale drawings?

Answer 20

1) Draw the forces acting on an object, to scale, ‘tip-to-top’.
2) Draw a straight line from the start of the 1st force to the end of the 2nd - this is the resultant force.
3) Measure the length of the resultant force on the diagram to find the magnitude. And the angle to find the force’s direction.

Question 21

When is an object in Equilibrium?

Answer 21

When the forces on it are balanced.

Question 22

What elasticity movements transfer energy?

Answer 22

Stretching, compressing or bending.

Question 23

When is work done in terms of elasticity?

Answer 23

When a force stretches or compresses an object and causes energy to be transferred to the elastic potential energy store of the object.

Question 24

How is extension linked to force?

Answer 24

Extension is directly proportional to force. But this stops working when the force is great enough.

Question 25

What quantity is speed and velocity?

Answer 25

Speed is scalar. Velocity is a vector.

Question 26

What is the difference between speed and velocity?

Answer 26

Speed and velocity are both how fast you are. But velocity gives the direction as well.

Question 27

What is acceleration?

Answer 27

Change in velocity in a certain amount of time.

Question 28

What is uniform acceleration?

Answer 28

Speeding up or down at a constant rate.

Question 29

What happens to drag when speed increases?

Answer 29

Drag increases.

Question 30

What is drag?

Answer 30

The resistance you get in a fluid (gas/liquid). Air resistance is a type of drag.

Question 31

What is the most important factor in reducing drag?

Answer 31

Keeping the shape of the object streamlined.

Question 32

What does terminal velocity depend on?

Answer 32

Shape and area.

Question 33

What is Newton’s first law?

Answer 33

Says that a resultant force is needed to make something start moving, speed up or slow down.

Question 34

What will a non-zero resultant force always do?

Answer 34

Always produce acceleration (or deceleration) in the direction of the force.

Question 35

What is inertia?

Answer 35

The tendency for motion to remain unchanged.

Question 36

What does Newton’s third law say?

Answer 36

When two objects interact, the forces they exert on each other are equal and opposite.

Question 37

What is the stopping distance equation?

Answer 37

Thinking distance + braking distance.

Question 38

Thinking distance is affected by?

Answer 38

Your speed

Your reaction time.

Question 39

What is braking distance affected by?

Answer 39

Your speed.
The weather/road surface.
Condition of tyres.
Brakes quality.

Question 40

What does braking rely on?

Answer 40

Friction between the brakes and wheels.

Question 41

Equation for momentum?

Answer 41

Mass x velocity.

Question 42

What is conservation of momentum?

Answer 42

In a closed system, the total momentum before an event is the same as after the event.