Mechanics 2

Question 1

Is the period of the simple pendulum directly proportional to its length? explain

Answer 1

no, T² α l

Question 2

measuring g from a pendulum graph x axis

Answer 2

T²

Question 3

measuring g from a pendulum graph y axis

Answer 3

length

Question 4

measuring g from a pendulum graph g

Answer 4

4 π² x slope

Question 5

How is a pendulum set up so that it swings freely

Answer 5

one end of a string is tied to the pendulum bob and the other fixed end is passed through a split cork attached to a retort stand. pull the bob a little to one side and allow it to swing. keep the angle of the swing small

Question 6

state isaac Newton’s law of universal gravitation

Answer 6

any two point masses in the universe attract each other with a force that is directly proportional to the product of the masses and inversely proportional to the square if the distance between them

Question 7

equation for Isaac Newton’s law of universal gravitation

Answer 7

F = GMm/R²

Question 8

acceleration due to gravity at the surface of the earth

Answer 8

g

Question 9

forces which cause the earth to spin

Answer 9

gravitational attraction = centripetal force

Question 10

period of communication of a satellite

Answer 10

24 hours

Question 11

describe how the centre of gravity of the meter stick is found

Answer 11

balance the meter stick on a suitable fulcrum eg. a wedge. not and record the position on the meter stick that balances the stick horizontally ie. position of equilibrium

Question 12

Hook’s law

Answer 12

for an object stretched or compressed, the restoring force is directly proportional to the displacement F = -ks

Question 13

3 examples of SHM

Answer 13

stretched elastic
swinging pendulum through a small angle
vibrating tuning fork

Question 14

number of oscillations per minute

Answer 14

frequency. 1/T

Question 15

describe how to get data to verify Boyle’s law

Answer 15

diagram (pressure gauge, scale to read volume, syringe)
get volume by reading scale
pressure by reading gauge
change by moving piston in or out

Question 16

graph of boyles law x axis

Answer 16

1/V

Question 17

graph of boyles law y axis

Answer 17

Pressure

Question 18

verifying boyles law, how to keep temperature constant

Answer 18

after adjusting the piston allow a few minutes to pass before the new values of pressure and volume, to keep at room temperature

Question 19

what provides the centripetal force to keep the earth moving around the sun

Answer 19

the gravitational force (pull) of the sun on the earth

Question 20

centripetal force

Answer 20

f = mv² / r

Question 21

angular velocity

Answer 21

θ/t

Question 22

centripetal force

Answer 22

the force acting towards the centre of a circle for an object undergoing circular motion

Question 23

why does the frequency of the received radio signal change as the satellite orbits the sun

Answer 23

this is an example of the doppler effect, as it travels towards the earth a higher frequency is observed and as it travels away from the earth a lower frequency is observed

Question 24

why is an inextensible string used in a pendulum

Answer 24

so that the length remains constant

Question 25

accuracy for pendulum

Answer 25

keep the angle of the swing small

Question 26

velocity

Answer 26

rate of change of momentum

Question 27

derive ω x r = v

Answer 27

θ = s/r and ω = θ/t
ω = (s/r)/t = s/(r x t)
v = s/t -> ω = v/r
ω x r = v

Question 28

T =

Answer 28

2π /ω

Question 29

define pressure

Answer 29

force per unit area

Question 30

is pressure scalar or vector and explain

Answer 30

scalar as it acts in all directions

Question 31

state Boyle’s law

Answer 31

for a fixed mass of gas at a constant temperature the pressure of a gas is inversely proportional to the volume of a gas

Question 32

if the volume is 3 times smaller what is the pressure

Answer 32

3 times bigger

Question 33

pressure =

Answer 33

ρgh

Question 34

why does the sphere obeying Hooke’s law oscillate with simple harmonic motion

Answer 34

a = (-ks)/m

a α -s, condition for simple harmonic motion

Question 35

explain why after an orbit a satellite will be above a different point on the earth’s surface

Answer 35

its period of rotation may not be the same as that of the earth

Question 36

describe the movement of a sphere on a spring pulled down and explain

Answer 36

it will undergo simple harmonic motion, the acceleration is proportional to the displacement

Question 37

distance between earth and other planet

Answer 37

measured from centre of each planet!!!

Question 38

how to find acceleration due to gravity at a distance away from the earth (gs)

Answer 38

divide gs (written in formula) by g (GM/r² )

Question 39

when is an astronaut actually weightless

Answer 39

when gravity due to earth is equal to gravity due to other planet or moon

Question 40

why is there no atmosphere on the moon

Answer 40

the gravitational force is too weak to sustain an atmosphere

Question 41

moment of a force

Answer 41

force x perpendicular distance from axis to line of action of force

Question 42

formula for f and ω

Answer 42

F = ω/2π

Question 43

minimum force of a vibrating object occurs when

Answer 43

maximum displacement

Question 44

maximum force of a vibrating object occurs when

Answer 44

minimum displacement

Question 45

measure the length of a string in a pendulum

Answer 45

string + radius of bob

Question 46

how to measure diameter of a bob

Answer 46

vernier callipers

Question 47

how to find periodic time

Answer 47

measure time for several oscillations, divide by the number of oscillations