Mechanics

Question 1

List the suvat equations

Answer 1

v=u +at
s=(u+v)/2 t
s=ut + 1/2a*t^2
v^2=u^2 + 2as

Question 2

What is a free body diagram

Answer 2

a free body diagram whoch shows all the forces that act on an object

Question 3

what is netwon’s first law

Answer 3

an object will remain at rest or travelling at a constant velocity, until it experiences a resultant force

Question 4

what is newton’s second law

Answer 4

F=ma
the acceleration of an object is proportional to the resultant force experienced by the object
MASS MUST STAY CONSTANT if the other two is known

Question 5

how to prove N1L using N2L

Answer 5

if resultant force is 0 and acceleration is 0
F=0
a=0
0=m*0
0=0

Question 6

how does terminal velocity occur

Answer 6

when the frictional forces acting on an object and the driving forces are equal, so no resultant, no acceleration, so it travels at constant velocity

Question 7

what is newton’s third law

Answer 7

for each force experienced by an object, the object exerts an equal and opposite force (reaction forces)

Question 8

equation for momentum

Answer 8

momentum = mass * velocity

Question 9

unit for momentum

Answer 9

kg m s^-1

Question 10

what is the principle of conservation of linear momentum

Answer 10

momentum is always conserved in any interaction where forces act.
momentum before = momentum after

Question 11

how does force and momentum link

Answer 11

force is the rate of change of momentum

F=change in momentum/change in time period

Question 12

equation for moment

Answer 12

moment = force * perpendicular distance from pivot

Question 13

what is the principle of moments

Answer 13

sum of anticlockwise moments = sum of clockwise moments ,when there is no external forces acting upon it

Question 14

what is the centre of gravity

Answer 14

the point which the gravity appears to act

Question 15

where does the weight act upon the object

Answer 15

the centre of gravity

Question 16

formula for work done (linear)

Answer 16

W.d. = force * distance

Question 17

formula for work done (trig)

Answer 17

W.d. = force * distance * cos θ

Question 18

what is kinetic energy

Answer 18

the energy that an object has due to its motion

Question 19

what is gravitational potential energy

Answer 19

the energy that an object has due to its position in a gravitational field

Question 20

what is the principle of conservation energy

Answer 20

energy can not be created or destroyed
total energy in a closed system stays constant

Question 21

what is power

Answer 21

the rate of energy transfer

Question 22

alternative formula for power

Answer 22

Power = force * velocity

P = W/t
P = (Fd)/t
P = Fv

Question 23

What is impulse

Answer 23

change in momentum

Question 24

impulse in force time graph

Answer 24

area under graph

Question 25

energy in elastic collisions

Answer 25

all kinetic energy is conserved

Question 26

What must always be true when using the SUVAT equations of motion?

Answer 26

The acceleration must be uniform - if the acceleration is changing, the equations are not valid.

Question 27

What does the gradient of a distance-time graph represent?

Answer 27

Speed

Question 28

What does the gradient of a displacement-time graph represent?

Answer 28

Velocity

Question 29

What does the gradient of a velocity-time graph represent?

Answer 29

Acceleration.

Question 30

Describe the shape of a velocity-time graph for an object travelling with uniform acceleration.

Answer 30

If acceleration is constant, the gradient of the velocity-time graph will be constant and so it will form a straight line graph.

Question 31

Describe the shape of a velocity-time graph for an object travelling with non-uniform acceleration.

Answer 31

If acceleration is not constant, the gradient of the velocity-time graph will change and so it will form a curve.

Question 32

Compare the velocity-time graphs for a uniformly accelerating and a uniformly decelerating object.

Answer 32

● For an accelerating object, the gradient will be positive ● For a decelerating object, the gradient will be negative

Question 33

Give five examples of scalar quantities.

Answer 33

1. Distance 2. Speed 3. Mass 4. Energy 5. Temperature

Question 34

Give five examples of vector quantities.

Answer 34

1. Displacement 2. Velocity 3. Acceleration 4. Momentum 5. Force

Question 35

How is a vector quantity represented on a diagram?

Answer 35

● As an arrow ● The direction of the arrow represents the direction of the quantity ● The length of the arrow represents the magnitude of the quantity