Mechanics

Question 1

what is a scalar?

Answer 1

quantities that only have magnitude

Question 2

what is a vector?

Answer 2

quantities with magnitude and direction

Question 3

what is the equation for speed?

Answer 3

speed = distance/time

Question 4

what is acceleration?

Answer 4

the rate of change of velocity

Question 5

what is the acceleration of gravity?

Answer 5

9.81ms-1

Question 6

what is the gradient of an acc-time graph?

Answer 6

velocity

Question 7

what is the gradient of a displacement-time graph?

Answer 7

velocity

Question 8

what is the area under a vel-time graph?

Answer 8

displacement

Question 9

what is the gradient of a vel-time graph?

Answer 9

acceleration

Question 10

how can a resultant vector be found?

Answer 10

by adding them (use pythagoras if at a right angle)

Question 11

how to find an angle?

Answer 11

use trigonometry

Question 12

what is the equation for weight?

Answer 12

weight (N) = mass (kg) x gravity (Nkg-1)

Question 13

what is work done?

Answer 13

energy transferred by a force in the direction of a force

Question 14

what is the equation for work done?

Answer 14

work done (J) = force (N) x distance (m)

Question 15

what should you do if the force is not parallel to the distance?

Answer 15

must find component parallel (W = Fdcos)

Question 16

what is power?

Answer 16

rate at which work is done on an object

Question 17

what is Newtons 1st Law?

Answer 17

if no resultant force is acting on an object, the object is stationary/moving at a constant acceleration

Question 18

what is Newtons 2nd Law?

Answer 18

force is proportional to the rate of change of momentum

Question 19

what is Newtons 3rd Law?

Answer 19

every action has an equal and opposite reaction

Question 20

what is the equation of momentum?

Answer 20

force x time = change in momentum x velocity

Question 21

what happens if there is no frictional force?

Answer 21

GPE at the top is equal to KE at the bottom

Question 22

what happens if there is a frictional force?

Answer 22

GPE does not equal KE

Question 23

what is the final velocity when an object is at its highest point?

Answer 23

0ms-1

Question 24

what is the acceleration of gravity?

Answer 24

9.81ms-2

Question 25

what is the equation of vertical velocity of momentum in 2D?

Answer 25

M(A)xV(A)sin(θ(A)) = M(B)xV(B)sin(θ(B))

Question 26

what is the equation of horizontal velocity of momentum in 2D?

Answer 26

M(A)xV(A) = (M(A)xV(A)cos(θ(A)) + (M(B)xV(B)cos(θ(B))

Question 27

what is drag?

Answer 27

frictional force acting on an object when in a fluid

Question 28

what factors affect drag?

Answer 28

- viscosity of the liquid - speed of object (proportional) - size and shape of object (larger SA -> larger drag)

Question 29

what is terminal velocity?

Answer 29

when frictional force is equal to the driving force

Question 30

how does terminal velocity look like on a vel-time graph?

Answer 30

when line becomes straight

Question 31

how does terminal velocity look like on an acc-time graph?

Answer 31

when line reaches x-axis

Question 32

how to explain the terminal velocity of a car?

Answer 32

- resultant force is equal to the driving force - as speed increases, friction increases, decreasing acceleration and resultant force - when resultant force is 0, the car has reached terminal velocity

Question 33

how to explain the terminal velocity of a skydiver?

Answer 33

- the persons weight is equal to their resultant force - as their speed increases as they fall, the drag increases, decreasing the acceleration and resultant force - when the weight and drag are equal, the resultant force is 0 - person is at terminal velocity - when they open the parachute, the drag increases - this means drag is greater than the weight - person slows speed until weight is equal to drag again - new lower terminal velocity

Question 34

what is density?

Answer 34

mass per unit volume

Question 35

what is the equation for density?

Answer 35

density = mass/volume

Question 36

what is pressure?

Answer 36

force per unit area

Question 37

what is the unit for pressure?

Answer 37

Pascals (Pa) = Nm-1

Question 38

what is fluid pressure?

Answer 38

combined force the particles of a fluid exert on the surface

Question 39

what is the equation for fluid pressure?

Answer 39

pressure = depth x density x gfs

Question 40

what happens when a fluid has a greater fluid density?

Answer 40

it has a greater pressure due to more collisions

Question 41

what happens when a fluid has a greater depth?

Answer 41

number of particles above that point increases, therefore there is a greater pressure

Question 42

what is upthrust?

Answer 42

upwards force that a submerged or partially submerged object experiences in a fluid

Question 43

what is Archimedes principle?

Answer 43

upthrust is equal to the weight of water displaced

Question 44

what are the equations of power?

Answer 44

power = energy/time power = work done/time power = force x velocity

Question 45

how do you know when a collision is inelastic?

Answer 45

- kinetic energy is not conserved - when both objects stick together

Question 46

what does a force-time graph have the same shape as?

Answer 46

acc-time graph

Question 47

what is the area under a force-time graph?

Answer 47

impulse

Question 48

what does a momentum-time graph have the same shape as?

Answer 48

vel-time graph

Question 49

what is the gradient of momentum-time graph?

Answer 49

resultant force

Question 50

how can i work out momentum?

Answer 50

mass (kg) x velocity (ms-1)

Question 51

what is impulse equal to?

Answer 51

change in momentum

Question 52

how to work out tension when an object acc upwards?

Answer 52

T (N) = m (kg) [g + a] (ms-2)

Question 53

how to work out tension when an object acc downwards?

Answer 53

T (N) = m (kg) [g - a] (ms-2)

Question 54

how to work out tension when an object isnt acc?

Answer 54

T (N) = m (kg) x a (ms-2)

Question 55

when will you need to use a centripetal force?

Answer 55

when an object moves in a circular motion at constant speed

Question 56

what is the equation for centripetal force?

Answer 56

mass (kg) x radius (m) x (velocity of object / radius)^2