Forces

Question 1

what is a scalar?

Answer 1

quantity with magnitude only

Question 2

what is a vector?

Answer 2

quantity with both magnitude and direction

Question 3

what is distance?

Answer 3

how far an object moves (m) - scalar

Question 4

what is displacement?

Answer 4

distance an object moves, measured in straight line from start point to end point and in the direction of that line - vector

Question 5

what is speed?

Answer 5

distance an object moves per second (m/s) - scalar

Question 6

what is velocity?

Answer 6

speed in a given direction (m/s)- vector

Question 7

what is the resultant force?

Answer 7

overall force acting on an object

Question 8

the steeper a distance time graph; ….

Answer 8

the faster the motion

Question 9

what does a horizontal line on a distance time graph mean?

Answer 9

the object is stationary

Question 10

what does a a curved line on a distance time graph mean?

Answer 10

the object is accelerating or decelerating

Question 11

the steeper a velocity time graph;…

Answer 11

the greater the acceleration

Question 12

what does a horizontal line on a velocity time graph mean?

Answer 12

the object is at a constant velocity

Question 13

what does a a downward sloping line on a velocity time graph mean?

Answer 13

the object is decelerating

Question 14

what is the gradient on a velocity time graph?

Answer 14

acceleration

Question 15

what is the area under the line on a velocity time graph?

Answer 15

displacement

Question 16

how do you calculate velocity?

Answer 16

displacement / time.

Question 17

all objects with ____ produce a gravitational field.

Answer 17

mass

Question 18

what gives an object a greater gravitational field?

Answer 18

a greater mass

Question 19

what is weight?

Answer 19

force acting on an object due to gravity (N)

Question 20

what happens When a force acts on an object?

Answer 20

the object may change shape by bending, stretching or compressing - or a combination of all three shape changes.

Question 21

what is A change in shape called?

Answer 21

deformation

Question 22

what happens to elastic deformation when the force is removed?

Answer 22

it is reversed

Question 23

what happens to inelastic deformation when the force is removed?

Answer 23

it is not fully reversed when the force is removed - there is a permanent change in shape

Question 24

what is hooke’s law?

Answer 24

force (N)= spring constant (N/m) × extension (m)

Question 25

what is the spring constant?

Answer 25

a measure of the stiffness of a spring up to its limit of proportionality.

Question 26

what is the limit of proportionality?

Answer 26

the point beyond which Hooke's law is no longer true when stretching a material

Question 27

what is the elastic limit of a material?

Answer 27

the furthest point it can be stretched or deformed while being able to return to its previous shape.

Question 28

when does a moment occur?

Answer 28

when a force is applied at a distance from a pivot

Question 29

how do you calculate a moment?

Answer 29

force x distance

Question 30

for an object at equilibrium, the sum of the clockwise moments = ?

Answer 30

the sum of the anticlockwise moments

Question 31

what is the centre of mass?

Answer 31

the point at which the mass can be thought to be concentrated - the point from which the weight of an object acts

Question 32

if an object is stable, where will the line of action fall?

Answer 32

inside the base

Question 33

do big gears have a bigger or smaller moment?

Answer 33

bigger - as the distance to the pivot is greater

Question 34

do big gears rotate at higher or lower speeds than small gears?

Answer 34

lower

Question 35

what happens in low gear?

Answer 35

a small gear turns a larger gear which gives a low speed and high turning effort

Question 36

what happens in high gear?

Answer 36

a large gear turns a smaller gear which gives a high speed and low turning effort

Question 37

what is a fluid?

Answer 37

anything which can flow

Question 38

how do you calculate pressure?

Answer 38

force / area

Question 39

what is pressure measured in?

Answer 39

pascals, Pa, or N/m^2

Question 40

how do you calculate pressure due to a column of liquid ?

Answer 40

density of liquid x height of column x strength of gravity

Question 41

what is upthrust?

Answer 41

the upwards force which acts on an object in any fluid, which occurs because the pressure at the bottom of the object is greater than the pressure at the top; if the upthrust is bigger than the weight, the object will rise

Question 42

what is stopping distance?

Answer 42

thinking distance + braking distance

Question 43

what are some factors that affect thinking distance?

Answer 43

- age - alcohol - drugs - distractions - speed - tiredness

Question 44

what are some factors that affect braking distance?

Answer 44

- mass of car - speed - road surface - condition of brakes

Question 45

what is braking distance proportional to?

Answer 45

speed of vehicle^2

Question 46

what is newton's first law?

Answer 46

objects stay at rest or move with constant velocity unless acted upon by a resultant force

Question 47

what is newton's second law?

Answer 47

f = m a

Question 48

what is newton's third law?

Answer 48

when two objects interact, they exert an equal and opposite force on each other

Question 49

what is acceleration?

Answer 49

change in velocity of an object over time (m/s^2)

Question 50

what is inertia?

Answer 50

tendency of objects to continue in uniform motion

Question 51

what happens at terminal velocity?

Answer 51

the object moves at a steady speed in a constant direction because the resultant force acting on it is zero.

Question 52

what are the three stages as an object falls through a fluid?

Answer 52

- at the start, the object accelerates downwards due to the force of gravity - as the object's speed increases, frictional forces such as air resistance or drag increase - at terminal velocity, the weight of the object due to gravity is balanced by the frictional forces, and the resultant force is zero

Question 53

how do you calculate momentum?

Answer 53

mass (kg) x velocity (m/s)

Question 54

what is the principle of conservation of momentum?

Answer 54

in a closed system, the total momentum before the event is equal to the total momentum after. if momentum is not conserved in an event such as a collisions it is because external forces are acting on the objects