P8 Forces

Question 1

what are scalar quantities?

Answer 1

Quantities with magnitude only
They do not have direction

Question 2

what is a vector quantity?

Answer 2

quantities which have both direction and magnitude

Question 3

what is displacement?

Answer 3

distance in a specific direction

Question 4

how can vectors be represented?

Answer 4

using an arrow.
the length represents the magnitude and the direction of the arrow represents the direction

Question 5

what is a force?

Answer 5

a push or a pull that acts on an object due to the interaction with another object

Question 6

what type of quantity is a force?

Answer 6

a vector

Question 7

what is the unit of force?

Answer 7

N (newton)

Question 8

what is a contact force?

Answer 8

when the two objects are physically touching

Question 9

what is a normal contact force?

Answer 9

when two objects are in direct contact with one having a force of weight and the other providing an upwards force to the other object.

Question 10

what in a non-contact force?

Answer 10

when the two objects are physically separated

Question 11

what are some examples of non-contact forces?

Answer 11

gravitational force, electrostatic force, magnetic force

Question 12

what is mass?

Answer 12

how much matter an object has. It does not depend on where the object is

Question 13

what is the weight of an object?

Answer 13

the force acting on it due to gravity. this is dependant of were an object is

Question 14

what is g?

Answer 14

the gravitational field strength of a location. it is a measure of the force of gravity in a particular location

Question 15

what is the formula for weight?

Answer 15

W = m x g

Question 16

how are weight and mass related?

Answer 16

they are directly proportional
weight = k x mass

Question 17

where does weight act on an object?

Answer 17

on a single point known as the centre of mass

Question 18

what is the resultant force?

Answer 18

a single force that has the same effect as all the original forces acting together

Question 19

what happens when the resultant force is 0?

Answer 19

the forces are balanced so the object is either stationary or moving at constant speed

Question 20

what is a free body diagram?

Answer 20

when the object involved is shown as a point
the forces are drawn as arrows from the point

Question 21

what is a vector diagram?

Answer 21

a scale drawing showing all of the forces involved

Question 22

what is resolving of a force?

Answer 22

when a single force is broken down (resolved) into component forces at right angles to each other

Question 23

what is work?

Answer 23

when energy is transferred by a force

Question 24

what is the formula for work?

Answer 24

W = F x s (distance)

Question 25

what must the distance be when calculating work done?

Answer 25

it must be in the line of action of the force (the distance must be in the same direction of the force ie. use the vertical distance travelled for gravity which is exerted vertically)

Question 26

what does 1 newton metre equal?

Answer 26

1 newton metre of work = 1 joule

Question 27

what is a moment?

Answer 27

the turning effect of a force

Question 28

what is the equation for moments?

Answer 28

Moment = F (force) x d (distance)

Question 29

what is the unit for a moment?

Answer 29

Nm (newton-metre)

Question 30

what does the distance have to be when calculating the moment of a force?

Answer 30

perpendicular from the line of action of the force to the pivot

Question 31

what is the pivot?

Answer 31

where the turning effect of a force is centred

Question 32

what is happening when two moments are balanced?

Answer 32

the anticlockwise moment = clockwise moment so a lever does not turn in one direction (it is balanced)

Question 33

why do some objects topple?

Answer 33

the weight of an object comes directly from the centre of mass. when the object is turned, there comes a point where the line of action of the force lies outside the base of the block and an unbalanced resultant/moment acting on the object. this causes the object to fall

Question 34

what is a force multiplier?

Answer 34

a lever used so that a weight or force can be moved by a smaller force

Question 35

what are gears used for?

Answer 35

transmitting the turning effect of a force

Question 36

what does the turning effect of a gear depend on?

Answer 36

the distance between the edge of the gear and the centre (radius)

Question 37

why is the work done by two gears of different sizes the same?

Answer 37

the smaller gear rotates more times than the larger one while the larger one has a greater turning effect

Question 38

what does a low gear (small to big gears) give?

Answer 38

it gives a low speed and a high turning effect

Question 39

what does a high gear (large to small gear) give?

Answer 39

it gives high speed and low turning effect