Chapter 8

Question 1

what is displacement?

Answer 1

measures the distance and direction between a start and end point in a straight line

Question 2

what is a vector?

Answer 2

a physical quantity with a direction and size (magnitude)

Question 3

what is a scalar?

Answer 3

a physical quantity with just size (magnitude)

Question 4

difference between speed and velocity

Answer 4

speed is a scalar - it just has a size

velocity is a vector - it has size and direction

Question 5

typical speed of a person walking

Answer 5

1.5 m/s

Question 6

typical speed of a person running

Answer 6

3 m/s

Question 7

typical speed of a person cycling

Answer 7

6 m/s

Question 8

typical speed of a car

Answer 8

25 m/s

Question 9

typical speed of a train

Answer 9

55 m/s

Question 10

typical speed of a plane

Answer 10

250 m/s

Question 11

what is distance?

Answer 11

how far an object has moved

Question 12

what does the direction of an arrow represent?

Answer 12

the direction of the vector quantity

Question 13

what does the length of the arrow represent?

Answer 13

the magnitude of the vector quantity

Question 14

what is a force?

Answer 14

a push or pull on an object because of its interaction with another object

Question 15

what is a contact force?

Answer 15

when two objects must touch eachother to interact

Question 16

Newton’s Third Law states:

Answer 16

when two objects interact with eachother, they exert equal and opposite forces on eachother

Question 17

what is the driving force on a car?

Answer 17

the force that makes it move

Question 18

what is force measured in?

Answer 18

Newtons (N)

Question 19

what is a resultant force?

Answer 19

a single force that has the same effect on the object as all the forces combined

Question 20

Newton’s First Law states:

Answer 20

if the forces acting on an object are balanced, the resultant force is 0
if the object is at rest, it stays stationery
if the object is moving, it keeps moving in the same direction with the same speed

Question 21

if an object i acted on by two unequal forces, the resultant force:

Answer 21

is equal to the difference between the two

is in the direction of the larger force

Question 22

what is a free-body force diagram?

Answer 22

it shows all the forces acting on an object without anything else being shown

Question 23

How to increase the moment? 2

Answer 23

Increasing the size of the force

increasing the distance from the pivot

Question 24

What is a moment?

Answer 24

The turning effect of a force

Question 25

How to get the maximum moment?

Answer 25

The force needs to be applied perpendicular to the spanner

Question 26

What is the load?

Answer 26

The weight of the object

Question 27

What is the effort?

Answer 27

The force we apply

Question 28

What is a force multiplier?

Answer 28

The effort we apply lifts a much bigger load

Question 29

Equation for moment

Answer 29

force x perpendicular distance from pivot

Question 30

How do bottle openers work?

Answer 30

The force you apply is further from the pivot than the edge of the cap. So, it acts as a force multiplier and we can lift the cap

Question 31

Why are racing cars so low to the ground?

Answer 31

So they don't overturn when they go round corners

Question 32

What is the centre of mass of an object?

Answer 32

The point at which its mass can be thought of as being concentrated

Question 33

When will a hanging object stop moving?

Answer 33

When its centre of mass is directly below the point of suspension

Question 34

How to find the centre of mass of a flat object?

Answer 34

Draw on the lines of symmetry | It is where these lines cross

Question 35

What is the principle of moments?

Answer 35

For an object that is not turning, the sum of all the clockwise moments about a point = the sum of all the anticlockwise moments about a point

Question 36

How to draw a parallelogram of forces?

Answer 36

Draw the forces to scale as adjacent sides of a parellelogram

Question 37

How to draw a scale diagram?

Answer 37

Work out the different forces acting on an object and the direction Decide on and write down a scale Draw suitable arrows to fit

Question 38

What conditions must be present for an object to be in equilibrium? 2

Answer 38

No resultant force | No turning effect on the object

Question 39

How to resolve a force?

Answer 39

SEE FLASHCARDS

Question 40

How do gears work?

Answer 40

SEE FLASHCARDS?

Question 41

Why would a ship being pulled by tugboats move at a constant velocity?

Answer 41

The combined tug of the boats is equal to the drag force so it doesn't accelerate but travels at a constant speed