Module 3

Question 1

What is displacement?

Answer 1

Displacement is the distance travelled in a particular direction and is a vector quantity, units of metres (m).

Question 2

What is instantaneous speed?

Answer 2

The speed of an object at a given moment in time, units of metres per second (ms^-1)

Question 3

What is average speed?

Answer 3

A measure of the total distance travelled in a given time, units of metres per second(ms^-1)

Question 4

What is velocity?

Answer 4

Displacement per unit time, units of metres per second (ms^-1)

Question 5

What is acceleration?

Answer 5

The rate of change of velocity and is a vector quantity, units of metres per second squared (ms^-2)

Question 6

How do you find the velocity from a displacement time graph?

Answer 6

The gradient

Question 7

What does the gradient of a velocity time graph represent?

Answer 7

Acceleration

Question 8

How do you find the displacement from a velocity time graph?

Answer 8

Area under the graph

Question 9

What are the four equations for constant acceleration?

Answer 9

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

Question 10

What equation is associated with Newton’s Second Law?

Answer 10

Force = Mass x Acceleration (F = Ma). Unit is in Newtons

Question 11

What is the equation for density?

Answer 11

ρ = m / v (density = mass / volume)

Question 12

How can you derive the formula for Gravitational Potential Energy?

Answer 12

W = Fd
f = ma
GPE = mad
as a = g and d = h
GPE = mgh

Question 13

Name some techniques and procedures used to investigate the motion and collisions of objects.

Answer 13

Cause a collision between two objects and measure the velocity of the two objects before and after using light gates.

Question 14

How do you find the elastic potential energy from a force-extension graph?

Answer 14

Calculate the area under the graph

EPE = 1/2(Fx)

Question 15

State the Archimedes’ Principle.

Answer 15

The upthrust on a body totally or partially immersed in a fluid is equal to the weight of fluid it displaces. p = hpg

Question 16

State Newton’s 1st Law.

Answer 16

A object remains stationary or travels at a constant velocity in a straight line unless a external force acts on it.

Question 17

State Newton’s 2nd Law.

Answer 17

The rate of change of momentum of an object is directly proportionally to the net force which acts on the object.

Question 18

State Newton’s 3rd Law.

Answer 18

If object A exerts a force on object B, then object B will exert an equal but opposite force on object A.

Question 19

What is the formula for power and its units?

Answer 19

Power = (Force x Distance) / Time
(P = Fd/t)
Power is measured in watts

Question 20

What are the factors affecting drag?

Answer 20

size, shape, weight, and texture of the surface of an object

Question 21

Unit of force?

Answer 21

Newton (N) Kgms^-2 (from F=ma)

Question 22

What is thinking distance?

Answer 22

distance travelled in the time between the driver seeing the danger and pressing the brakes proportional to the velocity

Question 23

What is braking distance?

Answer 23

distance travelled in the time between the driver hitting the brakes and the car stopping, proportional to the velocity squared

Question 24

What is stopping distance?

Answer 24

braking plus thinking distance

Question 25

What is terminal velocity?

Answer 25

when the weight downwards is equal to the drag force upwards

Question 26

Principle of moments

Answer 26

The sum of the anti clockwise moments is equal to the sum of the clockwise moments in rotational equilibrium

Question 27

Conservation of momentum

Answer 27

The total linear momentum before a collision is equal to the total linear momentum after a collision, provided no external forces are applied

Question 28

Couple of forces

Answer 28

Two equal and anti parallel forces, of the same type, acting about a pivot

Question 29

Torque

Answer 29

The turning effect of a force in circular motion (Force x perp. distance)

Question 30

Centre of mass

Answer 30

The single point in which all the mass of an object can be assumed to act through

Question 31

Centre of gravity

Answer 31

The single point in which all the weight of an object can be assumed to act through

Question 32

Derive KE

Answer 32

W=Fd v^2=u^2+2as
W=kg (nm^-2m) 1/2 v^2=as
W=m(0.5v^2)
KE=1/2mv^2

Question 33

Derive P=Fv

Answer 33

w=Fd
P=w/t
P=F(d/t)
P=Fv

Question 34

Derive gpe=mgh

Answer 34

W=Fd
gpe=Fd
gpe=mad
gpe=mgh

Question 35

Young modulus=?

Answer 35

FL/Ax = stress/strain

Question 36

p=mv what does this mean?

Answer 36

momentum=mass X velocity

Question 37

State Hooke’s law

Answer 37

the extension of an object is proportional to the force that causes it, provided that the elastic limit is not exceeded

(f∝x)

Question 38

A squared + B squared = C [Blank]

Answer 38

Squared

Question 39

What are the SI units of resistivity?

Answer 39

m^2 S A^-2

Question 40

What is the unit for work done?

Answer 40

Joules

Question 41

What is an impulse and what is the unit for it?

Answer 41

the rate of change of momentum.

Question 42

Define moment

Answer 42

The product of a force and the perpendicular distance of its line of action from the point or axis

Question 43

Define Torque

Answer 43

The turning moment due to a couple is the product of one of the forces and its perpendicular distance between them.

Question 44

Units for Torque?

Answer 44

Newton Metres

Question 45

Centre of Mass

Answer 45

The single point in an object in which all the mass of an object acts can be assumed to be situated

Question 46

Centre of Gravity

Answer 46

The single point of an object in which gravity is assumed to act upon

Question 47

Equilibrium

Answer 47

A condition when an object has a total net force of zero (e.g. Thrust - Drag = 0 therefore car is stationary/at constant velocity)

Question 48

When an object is in equilibrium, what can you do with three forces?

Answer 48

You can create a triangle (closed loop).

Question 49

Density

Answer 49

Mass per unit volume, kgm^-3