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

Question 4

difference between speed and velocity

Answer 4

speed is a scalar- it just has size

velocity is a vector - it has size and direction

Question 5

what is a distance

Answer 5

how far an object has moved

Question 6

what does the direction of an arrow represent

Answer 6

the direction of the vector quantity

Question 7

what does the length of the arrow represent

Answer 7

the magnitude of the vector quantity

Question 8

what is a force

Answer 8

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

Question 9

what is a contact

Answer 9

when two objects much touch eachother to interact

Question 10

Newton’s third law states:

Answer 10

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

Question 11

what is the driving force on a car

Answer 11

the force that makes it move

Question 12

what is force measured in

Answer 12

Newtons N

Question 13

what is a resultant force

Answer 13

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

Question 14

newtons first law states:

Answer 14

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 15

if an object is acted on by two unequal forces; the resultant force

Answer 15

is equal to the difference between the two

is in the direction of the larger force

Question 16

what is a freebody force diagram

Answer 16

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

Question 17

how to increase the moment

Answer 17

increasing the size of the force

increasing the distance from the pivot

Question 18

what is a moment

Answer 18

the turning effect of a force

Question 19

how to get the maximum moment

Answer 19

the force needs to be applied perpendicular to the spanner

Question 20

what is the load

Answer 20

the weight of the object

Question 21

what is the effort

Answer 21

the forces we apply

Question 22

what is a force multiplier

Answer 22

the effort we apply lifts a much bigger load

Question 23

equation for moment

Answer 23

force x perpendicular distance from pivot

Question 24

how do bottle openers work

Answer 24

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 25

why are racing cars so low to the ground

Answer 25

so they don't overturn when they go round corners

Question 26

what is the centre mass of an object

Answer 26

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

Question 27

when will a hanging object stop moving

Answer 27

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

Question 28

how to find the centre of mass of a flat object

Answer 28

draw on the lines of symmetry | it is where these lines cross

Question 29

what is the principle of moments

Answer 29

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

Question 30

how to draw a parallelogram of forces

Answer 30

draw the forces to scale as adjacent sides of a parallelogram

Question 31

how to draw a scale diagram

Answer 31

work out the different forces acting on an object and the direction. decide on and write down a scale. draw a suitable arrows to fit

Question 32

what conditions must be present for an object to be in equilibrium

Answer 32

no resultant force | no turning effect on th object

Question 33

why would a ship being pulled by tugboats move at a constant velocity

Answer 33

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