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Orbits
1
What force keeps the Moon in orbit around the Earth and the Earth in orbit around the
Sun?
2
The force of gravity acts between all masses in the universe:
(a) Write down three things that determine the size of the force of gravity between
two objects.
(b) What happens to the size of this force if the distance between the bodies is doubled?
3
Sketch the path of a comet around the Sun and show, with arrows, its direction of
motion. On your sketch mark the following points: (a) where the comet is moving
fastest and where it is moving slowest, (b) where the gravitational force is increasing
and where it is decreasing.
4
The space shuttle is used to carry communication satellites into orbit.
(a) Explain how both the space shuttle and the satellite remain in orbit around the
Earth.
(b) State and explain what happens to the size of the gravitational force on the space
shuttle when the satellite is released.
(c) If the space shuttle moved to a higher orbit what would happen to the size of this
force and what would happen to the time period of the shuttle around the Earth?
5
There are many different types of orbit that an artificial satellite can follow but the two
main types are (i) geostationary orbits and (ii) polar orbits.
(a) Explain the differences between these two types of orbit.
(b) Why are geostationary orbits more useful for telecommunication purposes than
polar orbits?
(c) Make two columns, one labelled ‘Geostationary orbit’ and the other labelled
‘Polar orbit’, and under these headings list as many uses of satellites in these orbits as
you can.
(d) What is the height of a geostationary orbit?
(e) Why do satellites with lower orbits travel faster?
Vectors and equations of motion
REMEMBER – ASK IF NOT SURE
1
Calculate the resultant velocity of the aeroplane below
260 m/s
Crosswind 50 m/s
2
Explain why speed is a scalar quantity and velocity is a vector quantity.
3
Calculate the vector sum of the following:
(a) 5 N
(b) 20 m/s
3N
60m/s
(c) 100 N
4
50 N
A motorcycle travelling at 10 m/s overtakes a car. It takes two seconds to overtake and
is travelling at 14 m/s when completed. How much distance was covered whilst
overtaking?
5
A plane touches down on the runway at 30 m/s and decelerates at 1.5 m/s2 until it stops.
How long must the runway be?
SUVAT questions
1. A car starts from rest and accelerates to 20 m/s in 4 seconds. Use v= u + at to
find the acceleration of the car
2
A ball is dropped from a shelf that is 10m from the ground. If the acceleration
is 10 m/s/s how long does it take to hit the ground? Use s= ut + 1/2at2
3. An aeroplane travelling at 50 m/s lands on a runway, coming to a stop with a
deceleration of 1.25 m/s/s. How long is the runway? Use v2 =u2 + 2as
Force and momentum
1
If a girl sits on a chair then she exerts a force downwards on the chair and the chair
exerts an equal and opposite force upwards on her. Her force is known as the ACTION
force and the chair’s force is known as the REACTION force. Also the chair legs ACT
downwards on the ground and the ground REACTS upwards on the chair legs.
Sketch the following diagrams and draw on as many ACTION and REACTION forces
as possible:
(a)
(b)
beam
10 kg
(c)
2
(d)
Write a paragraph about car safety features and, using the ideas about momentum, how
they reduce injuries in collisions between vehicles.
3
Sporting injuries are often caused by very rapid acceleration (or deceleration) of the
body. Try to explain why.
4
The driver of a 800 kg car travelling at 60 m/s applies her brakes and reduces her
velocity to 20 m/s. The braking takes place over a time of 4 s. Calculate:
(a) the car’s original momentum.
(b) the car’s final momentum.
(c) the braking force required.
5
Before
After
4 m/s
2 m/s
5 kg
3 kg
5 kg
3 kg
? m/s
The diagram shows two trolleys moving along a smooth track and colliding. On
collision they join together and move on. Using the figures shown in the diagram,
calculate the final velocity of the trolleys.
6
A stationary tank of mass 10 000 kg fires a 250 kg shell at a velocity of 200 m/s.
Calculate the recoil velocity of the tank.
7
Using ideas about conservation of momentum, explain how a large rocket can be
propelled forward by expelling hot gases from the rear of the rocket.
Satellite communication
1
A radio wave is being transmitted in the diagram below:
hill
(a) Sketch the diagram in your book show what happens as the waves pass the hill.
(b) What is this effect called?
(c) What happens to the waves when they reach the Earth’s upper atmosphere?
2
(a)
What frequencies of waves a reflected by the ionosphere.
(b) Explain why the strength of radio waves above 30 GHz is reduced as they travel
long distances.
3
Explain in detail how microwave communications are transmitted from one part of the
globe to another. A labelled diagram may help.
4
Compare radio waves and microwaves, how they are similar and what are the
differences between them?
Interference
1
What happens when two water waves overlap? Explain your answer.
2
If we stand just to the side of an open door we can hear a person speaking in a room but we
cannot see the person. We normally explain this by saying the sound diffracts as it goes
through the door but light travels in a straight lines. Describe how we can make light
diffract (or bend) and why it will not show this effect when travelling through the door.
3
A salesman for tinted front windscreens for customised cars states that the windscreens
he sells are not just tinted they are also polarised and that these windscreens only let
half the light in.
(a) What test could a customer carry out to see if the windscreens were polarised?
(b) Explain polarisation in terms of light waves.
(c) How can you plane polarise light?
4
Two loudspeakers can be set up as shown below. They both play exactly the same note.
loudspeaker 2
loudspeaker 1
1m
Line of students
When students stand in line a few metres in front of the loudspeakers some may hear a loud
note whilst others hear silence.
In terms of reinforcement and cancellation of waves, explain this variation in the
loudness of the note.
5
(a) National radio is broadcast by a series of neighbouring transmission aerials that
cover the whole country. Why do neighbouring aerials broadcast on slightly different
frequencies?
(b) Satellites receive microwave communication at a certain frequency but retransmit it
at a slightly different frequency. Why is there this difference in frequency?
Interference
1
What happens when two water waves overlap? Explain your answer.
2
If we stand just to the side of an open door we can hear a person speaking in
a room but we cannot see the person. We normally explain this by saying
the sound diffracts as it goes through the door but light travels in a straight
lines. Describe how we can make light diffract (or bend) and why it will not
show this effect when travelling through the door.
3
A salesman for tinted front windscreens for customised cars states that
the windscreens he sells are not just tinted they are also polarised and
that these windscreens only let half the light in.
(a) What test could a customer carry out to see if the windscreens were
polarised?
(b) Explain polarisation in terms of light waves.
(c) How can you plane polarise light?
4
Two loudspeakers can be set up as shown below. They both play exactly
the same note.
loudspeaker 2
loudspeaker 1
1m
Line of students
When students stand in line a few metres in front of the loudspeakers some may
hear a loud note whilst others hear silence.
In terms of reinforcement and cancellation of waves, explain this
variation in the loudness of the note.
5
(a) National radio is broadcast by a series of neighbouring transmission
aerials that cover the whole country. Why do neighbouring aerials
broadcast on slightly different frequencies?
(b) Satellites receive microwave communication at a certain frequency
but retransmit it at a slightly different frequency. Why is there this
difference in frequency?
Refraction of light
1
Complete the following sentences using the words given:
more
totally internally
reflected
red
fibre
endoscopes
bends
speed
refraction
dispersed
blue
critical
(a) When light travels from air into glass it _________ towards the
normal. This process is called __________ and is due to a change in
__________ of the light.
(b) White light is made up of __________ than one colour and when
these colours travel through glass they are ____________, with
__________ light being deviated more than _______ light.
(c) If light is travelling in glass and it strikes the surface at an angle
greater than the ________ angle then it will be __________
____________ _____________. Different materials have different
___________ angles. This effect is used in __________ optics and one
use of this is in ___________.
2
When light travels into a glass block it refracts.
(a) Draw a diagram to represent the light travelling through a glass
block.
(b) What happens to the speed of the light as it travels into the glass?
(c) Which way does the light bend when it slows down?
(d) What is the property of the material that controls the amount of
bending?
3
(a) Draw a diagram to show white light travelling through a 60º prism.
(b) Why does the light split up into different colours?
(c) What is this process called?
4
Light can be totally internally reflected (TIR).
(a) Draw three diagrams to show light passing from glass towards air
when it is
(i) incident at an angle less than the critical angle, (ii) incident at an angle
equal to the critical angle and (iii) incident at an angle greater than the
critical angle.
(b) Draw a diagram of a ray of light passing through an optical fibre.
(c) Write down two things about light that is undergoing TIR.
Optics
1
Projectors and magnifying glasses produce images that are larger than the
original objects. For both devices to work the object must be a precise
distance from the lens. What is the relationship between object and lens
in:
(a) a projector?
(b) a magnifying glass?
(Hint: it has something to do with the focal length of the lens.)
2
A film camera needs to focus on near and far objects. We do this by
changing the thickness of the lens in our eye. Cameras cannot do this so
how does it change focus a clear image?
3
An object with a height of 1.5 cm is placed 4 cm from a lens with a focal
length of 2.5 cm.
(a) Draw a diagram to show how the image is formed.
(b) How far from the lens is the image and what is its height?
(c) How can you tell the image will be magnified before you draw the
diagram?
4
A classroom overhead projector magnifies transparencies by five times.
If a transparency is 10 cm by 5 cm, what size is the image?
Refraction of light
1
Complete the following sentences using the words given:
more
totally internally
reflected
red
fibre
endoscopes
bends
speed
refraction
dispersed
blue
critical
(a) When light travels from air into glass it _________ towards the
normal. This process is called __________ and is due to a change in
__________ of the light.
(b) White light is made up of __________ than one colour and when
these colours travel through glass they are ____________, with
__________ light being deviated more than _______ light.
(c) If light is travelling in glass and it strikes the surface at an angle
greater than the ________ angle then it will be __________
____________ _____________. Different materials have different
___________ angles. This effect is used in __________ optics and one
use of this is in ___________.
2
When light travels into a glass block it refracts.
(a) Draw a diagram to represent the light travelling through a glass
block.
(b) What happens to the speed of the light as it travels into the glass?
(c) Which way does the light bend when it slows down?
(d) What is the property of the material that controls the amount of
bending?
3
(a) Draw a diagram to show white light travelling through a 60º prism.
(b) Why does the light split up into different colours?
(c) What is this process called?
4
Light can be totally internally reflected (TIR).
(a) Draw three diagrams to show light passing from glass towards air
when it is
(i) incident at an angle less than the critical angle, (ii) incident at an angle
equal to the critical angle and (iii) incident at an angle greater than the
critical angle.
(b) Draw a diagram of a ray of light passing through an optical fibre.
(c) Write down two things about light that is undergoing TIR.