Physics Term 1

Question 1

How do you read Vernier Callipers?

Answer 1

1. Close the callipers and record any zero error
2. Put object either inside or outside jaws and close them (outside jaws if measuring inside of an object, inside jaws if measuring outside)
3. Read the main scale
4. Read Vernier scale by matching up line and add onto the reading from the main scale
5. Subtract/Add zero error

Question 2

How do you read a Micrometer Screw Gauge

Answer 2

1. Close the screw gauge by turning the thimble, followed by the ratchet until it starts to click and record the zero error
2. Open the screw gauge, put the object between the anvil and spindle and gently close the screw gauge by turning the ratchet until it clicks
3. Read the main scale followed by the thimble scale
4. Record the final reading by adding or subtracting the zero error

Question 3

List the SI units

Answer 3

Time - seconds
Length - metres
Amount of Substance - mole
Mass - kilogram
Current - amperes
Temperature - kelvin
Light Intensity - candela

Question 4

List the prefixes

Answer 4

giga (G) = 10^9
mega (M) = 10^6
kilo (k) = 10^3
hecto (h) = 10^2
deka (da) = 10^1
deci (d) = 10^-1
centi (c) = 10^-2
milli (m) = 10 ^-3
micro(μ) = 10^-6
nano (n) = 10^-9
pico (p) = 10^-12

Question 5

Define accuracy

Answer 5

Accuracy is the measure of how close your measurements are to the true or accepted value.

Question 6

What two things does precision describe about your measurements?

Answer 6

1. Repeatibility

2. The number of decimal places given for your measurement

Question 7

What is the formula for absolute error & percentage error?

Answer 7

Absolute Error = measured value - accepted value

Percentage Error = (error in measurement / accepted value) x 100

Question 8

Define mass

Answer 8

Mass is the measure of a body’s inertia (its ability to resist changes in its acceleration. Mass is measured in kilograms. Mass does not change with location in the universe.

Question 9

Define weight

Answer 9

Weight is the effect of a gravitational field on a mass. Weight is a force measured in Newtons, N.

Question 10

What is the formula for weight?

Answer 10

weight (Newtons, N) = mass (kilogram, kg) x gravitational field strength (N kg^-1)

w = mg

Question 11

Define density

Answer 11

Density is defined as mass per unit volume of a substance. The standard units are kg / m^3 or g/cm^3. Remember 1 ml = 1 cm^3

Question 12

What is the formula for density?

Answer 12

density = mass / volume

ρ = m / v

Question 13

Define scalars and vectors

Answer 13

A scalar has a magnitude (size) only. A vector has both magnitude and direction. Time, Speed, Energy, Mass & Distance are all scalar quantities. Acceleration, Velocity, Momentum, Force, Weight & Displacement are vector quantities.

Question 14

What is the formula for average speed?

Answer 14

Average speed = distance travelled / time taken, the unit for average speed is m/s

Question 15

Define displacement

Answer 15

The distance moved in a stated direction.

Question 16

What is the difference between velocity and speed?

Answer 16

Velocity is the distance travelled in a unit time in a stated direction, whereas speed is just the distance travelled in unit time.

Question 17

What is the formula for velocity

Answer 17

Velocity = displacement / time taken

Question 18

Define acceleration

Answer 18

The change in the velocity in unit time.

Question 19

What is the formula for acceleration?

Answer 19

Acceleration = change in velocity / time taken.
a = (v - u)/t

Question 20

What is the gradient of a distance - time graph used to represent?

Answer 20

It represents the speed

Question 21

What is the gradient of a velocity - time graph used to represent?

Answer 21

Acceleration

Question 22

How do you calculate displacement in a velocity - time graph?

Answer 22

By finding the area under the graph.

Question 23

State the variables in the s u v a t equations

Answer 23

u = initial velocity
v = final velocity
t = time
s = displacement
a = constant value of acceleration

Question 24

State the 5 s u v a t equations

Answer 24

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

Question 25

Define a force

Answer 25

A force is a push or pull. It can cause a change in the body’s shape, speed or direction.

Question 26

What is a force arrow and what does this arrow show?

Answer 26

A force arrow is an arrow used to represent a force. The arrow shows the size of the force (the longer the arrow, the bigger the force) and also in which direction the force acts.

Question 27

State Newton’s first law

Answer 27

A body’s motion will remain at rest or in uniform motion unless acted upon by an external unbalanced force.

Question 28

State Newton’s second law

Answer 28

This can be simplified to F = m x a, where F is the resultant force on an object. However correctly stated, the formula should be F = dp / dt.

Question 29

State Newton’s third law

Answer 29

When a force acts on an object, another force of the same type, equal in size but opposite in direction acts on an object (i.e. every action has an opposite and equal reaction)

Question 30

State Hooke’s law

Answer 30

Extension of a spring is directly proportional to the stretching force applied. This is only true if the limit of the proportionality of the spring is not exceeded.
F ∝ x or F = kx. The force constant k tells us how stiff the string is.

Question 31

What are the two conditions for equilibrium?

Answer 31

1. The sum of the forces in all directions must be equal to zero (i.e. no resultant force)
2. The sum of all moments about any point must be equal to zero (i.e. clockwise moments equal anticlockwise moments)

Question 32

State the formula for centripetal force

Answer 32

F = mv^2/r

= m x w^2 x r

Question 33

State the formula for acceleration in circular motion

Answer 33

a = v^2/r

Question 34

State the formula for angular velocity

Answer 34

w = 2πf

= 2π/T

Question 35

State the formula for tangential velocity

Answer 35

v = wr

Question 36

Define moment

Answer 36

The turning effect of a force. Moment depends on the size (magnitude) of the force & the perpendicular distance between the line of action of the force and the turning point (pivot)

Question 37

State the formula for torque

Answer 37

Moment = Force x Perpendicular distance
M = Fd , measured in Nm

Question 38

What is the centre of mass?

Answer 38

The point through which the mass of an object appears to act

Question 39

How do you know if a body is stable?

Answer 39

A body is stable if, when tilted slightly, the line of action of its weight passes through its base.

Question 40

What is the formula for momentum?

Answer 40

Momentum  = mass x velocity
p = mv, measured in kg m/s

Question 41

Correctly state Newton’s second law

Answer 41

The rate of change of momentum of an object is proportional to the resultant force acting on the object and is in the direction of the force.

Question 42

State the formula for force in momentum

Answer 42

Force = change in momentum (kg m/s) / time taken for the change
= final momentum - initial momentum / time
taken for the change

Question 43

State the formula for impulse

Answer 43

Impulse = force x time, it is equal to the change in momentum. The unit is Newton Seconds

Question 44

State the law of conservation of momentum

Answer 44

the total momentum before the collision = total momentum after collision

m1 x u1 + m2 x u2 = m1 x v1 + m2 x v2

Question 45

Define pressure

Answer 45

The force per unit area acting perpendicular to a surface. Measured in pascals (Pa) or newtons/metre^2.
1 Pa = 1 N/m^2

Question 46

State the equation for pressure

Answer 46

Pressure = force / area
P = F/A

Question 47

State the equation for fluid pressure

Answer 47

Pressure = depth x density x gravitational field strength
P = h ρ g

Question 48

What is the atmospheric pressure?

Answer 48

1.01 x 10^5 Pa or 1 atmosphere (1 atm) or 760 mm Hg