Forces in action

Question 1

What is magnitude?

Answer 1

the size of a quantity

Question 2

what is a moment?

Answer 2

the turning effect of a force

Question 3

What is the equation to find a moment?

Answer 3

m= f x d (from the pivot)

Question 4

what is the line of action?

Answer 4

the line that a force acts along

Question 5

what are levers?

Answer 5

mechanisms that make ‘work’ easier to do

Question 6

why are they called force multipliers?

Answer 6

the increase the size of the moment of a force

Question 7

What happens when a low gear is chosen?

Answer 7

-small gear wheel driven by the engine shaft is used to turn a large gear on the output shaft
-turning effect of output shaft is greater than turning effect of engine shaft

Question 8

What happens when a high gear is chosen?

Answer 8

-large gear driven by engine shaft drives a smaller gear on the output shaft
-output shaft turns faster than the engine shaft so car moves at a higher speed
-turning effect of output shaft is lower than turning effect of engine shaft

Question 9

When a bicycle is travelling uphill, what gear should be used?

Answer 9

a low gear: though the large gear by the output shaft doesn’t turn as quickly as the smaller gear, the turning effect is doubled due to its larger radius so less force needs to be applied

Question 10

What is Newton’s second law?

Answer 10

if the forces acting on an object are balanced, the resultant force is 0

Question 11

what defines the centre of mass of an object?

Answer 11

the single point where the entire weight of the object can be considered to act

Question 12

How does suspended equilibrium work?

Answer 12

an object (take a swing) will remain stationary if its centre of mass is directly below the point of suspension because its weight doesn’t exert a turning effect

Question 13

What is the principle of moments for an object that is not turning?

Answer 13

the sum of all clockwise moments about a point = the sum of all anticlockwise moments about a point

Question 14

when is the parallelogram of forces used?

Answer 14

it is used to find the resultant force of an object that is experiencing forces that aren’t occurring along the same line of action

Question 15

How can you use the parallelogram of forces to calculate the resultant force?

Answer 15

the angle between the two adjacent sides must be the same as the angle that is between the two forces. You must use a scale to draw the forces and apply this scale to the resultant force which is the diagonal of the parallelogram from the origin

Question 16

What does it mean to ‘resolve a force’?

Answer 16

it means to break a force down into two perpendicular components

Question 17

Why would a car moving at a constant speed around a roundabout not have a constant velocity?

Answer 17

the direction that the car is moving in is constantly changing and velocity is a vector quantity

Question 18

how do you calculate acceleration?

Answer 18

a = v-u/ t

Question 19

how do you calculate work done?

Answer 19

work done = force x distance

Question 20

How do you calculate force?

Answer 20

force= spring constant x extension

Question 21

How do you calculate the moment?

Answer 21

moment= force x distance (perpendicular to the direction of the force)

Question 22

how do you calculate momentum?

Answer 22

momentum= mass x velocity

Question 23

how do you calculate resultant force?

Answer 23

resultant force= mass x acceleration

Question 24

what is acceleration measured in?

Answer 24

m/s^2

Question 25

what is momentum measured in?

Answer 25

Kgm/s

Question 26

how do you calculate distance travelled on a velocity-time graph?

Answer 26

the area under the line on a graph represents the distance

Question 27

What does Newton's second law say about acceleration?

Answer 27

acceleration is directly proportional to force and inversely proportional to the mass of the object

Question 28

What does Newton's third law state?

Answer 28

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

Question 29

what is inertia?

Answer 29

the tendency of an object to stay at rest or move at a constant velocity

Question 30

What is the inertial mass?

Answer 30

it is a measure of the difficulty of changing an object's velocity

Question 31

how is intertial mass calculated?

Answer 31

force/ acceleration

Question 32

what is terminal velocity?

Answer 32

Terminal velocity is the constant speed reached when air resistance equals weight, resulting in zero resultant force and no acceleration.

Question 33

How do you calculate stopping distance?

Answer 33

stopping distance = thinking distance + braking distance

Question 34

how does speed impact thinking distance?

Answer 34

thinking distance is directly proportional to speed so the higher the speed at which a vehicle drives, the greater the thinking distance

Question 35

How do substances that affect thinking time overall impact the stopping distance?

Answer 35

alcohol and drugs increase a person's reaction time which therefore increases their thinking distance (speed x reaction time) which increases their stopping distance

Question 36

is momentum a vector or scalar quantity?

Answer 36

vector

Question 37

what does the conservation of momentum state?

Answer 37

in a closed system, the total before an event is equal to the total momentum after an event

Question 38

Why are crumple zones useful in reducing impact of a crash?

Answer 38

their ability to compress increases the time taken for a collision to occur which significantly lessens the impact as shown through force= change in momentum (mass x velocity)/ time

Question 39

Why might the momentum of two objects, when moving in opposite directions, cancel out?

Answer 39

one is moving in a negative direction and the other in a positive direction and according to Newton's third law, they exert equal and opposite forces on eachother and so they cancel themselves out