Physics 1 Markers

Question 1

Units of joule?

Answer 1

N m (newton metres?

Question 2

Units of watt?

Answer 2

J s^-1 (joules per second)

Question 3

Units of newton?

Answer 3

Kg m s^-2 (kilogram meters per second squared)

Question 4

Scalar vs vector

Answer 4

Scalar: only has magnitude
Vector: has magnitude and direction

Question 5

List 5 scalar and 3 vector quantities

Answer 5

Scalar: density, energy, time, power, speed,

Vector: acceleration, weight, displacement

Question 6

State Hooke’s law.

Answer 6

Extension is proportional to force (applies as long ad elastic limit is not exceeded)

Question 7

Explain what plastic deformation is.

Answer 7

Material is permemantly deformed, even after stress/force is removed.

Question 8

Define “ultimate tensile strength” of a material.

Answer 8

Maximum stress a material can withstand before fracture.

Question 9

State what the gradient of a force extenion graph represents?

Answer 9

Force constant/spring constant,

K.

Question 10

How do you find work done on a force extension graph?

Answer 10

Area under line.

Question 11

Define the Young Modulus of a material and state when it applies.

Answer 11

Stress/Strain.

As long as elastic limit isnt exceeded/hookes law obeyed/linear region of stress against strain graph.

Question 12

What form of energy is stored in metal wire when it is extended by a force?

Answer 12

Elastic potential or strain(energy)

Question 13

What is the forcd constant of a spring?

Answer 13

Force per unit extension.

Question 14

State 2 pairs of scalar quantities with the same units.

Answer 14

Pressure and stress
Moment and torque
Energy and work done

Question 15

What is meant by terminal velocity?

Answer 15

Max velocity of a falling object when drag=weight.

Question 16

Define velocity.

Answer 16

Rate of change of displacement.

Question 17

Define work done by a force.

Answer 17

Work done= force x distance moved in direction of force.

Question 18

Define density.

Answer 18

Mass per unit volume.

Question 19

Define newton.

Answer 19

Net force when 1kg of mass hass acceleration of 1 ms^2.

Question 20

Define braking distance.

Answer 20

Distance travelled from time brakes are applied to stop of car.

Question 21

State factors which increase braking distance.

Answer 21

Greater mass
Worn brakes/faulty
Road surface
Gradient of road

Question 22

State principle of moments.

Answer 22

“For equilibrium of an object, clockwise moments=anticlockwise moments about the same point”

Question 23

Define moment of a force.

Answer 23

Moment= force × perpendicular distance from point or pivot.

Question 24

Does mass of a particle change as it approaches speed of light?

Answer 24

Yes, it increases.

Question 25

What technique does GPS use to locate position of cars?

Answer 25

Trilateration.

Question 26

What is meant by centre of gravity of an object?

Answer 26

Point in which entire weight of object seems to act.

Question 27

What is meant by a white dwarf

Answer 27

left over core of a Red Giant

Question 28

Formula connecting arcsecs and parsecs

Answer 28

angle in arcsec= 1/distance in pc

Question 29

What is meant by intensity

Answer 29

Power per unit area. I=P/A

Question 30

Formula for calculating age of universe

Answer 30

t=1/Hubbles constant

Question 31

What is big bang and name 2 pieces of evidence for it

Answer 31

Explosion which created the universe. Background radiation at 1 or 2 kelvin. Primordial elements.

Question 32

Doppler Effect relations formula

Answer 32

v/c = ΔWL/WL = Δf/f

Question 33

Cosmological Principle

Answer 33

Universe is homogeneous and isotropic

Question 34

Define Homogeneous and Isotropic

Answer 34

Homogeneous:uniform density
Isotropic: Same in every direction

Question 35

What is background radiation and how does it link to big bang

Answer 35

Intensity is same in all directions, about 2k, microwaves show that universe has cooled since big bang. “echo of the big bang”

Question 36

3 properties of black holes

Answer 36

infinite density, light cant escape, singularity