Mechanics

Question 1

given constant acceleration, we have 5 quantities of motion - suvat, which stands for

Answer 1

s = displacement
u = initial velocity
v - final velocity
a = acceleration
t = time

Question 2

modelling assumption

Answer 2

particle :
- mass of object concentrated at a single point
- rotational forces/air resistance can be ignored

smooth/light pulley
- no friction, means tension is the same on either side of the pulley
- pulley has no mass

rod:
- mass is concentrated along the line

peg/support
- dimensionless and fixed. can be rough or smooth

uniform body - mass is concentrated at a single point

rough surface - object in contact with the surface experience a frictional force

smooth surface - no friction

inextensible string - acceleration is the same

Question 3

earth gravity number

Answer 3

9.8

Question 4

units

Answer 4

mass - kg
length/displacement - m
speed / velocity - m s ^-1
acceleration - ms^-2
force/weight - N (kg m s^-2)

Question 5

how to convert to vector form from scalar form

Answer 5

use basic trig to find the x and y

Question 6

how to convert from vector to scalar

Answer 6

find the magnitude

Question 7

velocity and speed

Answer 7

velocity is vector
speed is scalar

Question 8

average velocity equation

Answer 8

displacement from starting point/time taken

Question 9

average speed equation

Answer 9

total distance travelled/time taken

Question 10

acceleration is

Answer 10

the rate of change of velocity

Question 11

the area under a velocity time graph is…

Answer 11

the distance travelled

Question 12

differentiating displacement gives…

Answer 12

velocity, and integrating velocity gives displacement

Question 13

deceleration =

Answer 13

gradient

Question 14

deceleration =

Answer 14

gradient

Question 15

deceleration =

Answer 15

gradient

Question 16

weight equation

Answer 16

W = mg (mass x gravity)

Question 17

what is the normal reaction

Answer 17

a force that acts perpendicular to the surface

Question 18

newtons 1st law of motion

Answer 18

states that an object at rest will stay at rest
- an object moving with constant velocity will remain at that velocity
- unless an unbalanced force acts on that object

Question 19

newtons second law

Answer 19

F=ma

Question 20

if a particle is at equilibrium…

Answer 20

• it’s at rest or moving at constant velocity
• there is no resultant force
• left = up and right=down