11-14 Sample answers drawn from a number of different files
The questions are shown in black type with the answers in
bold blue1. If you wanted to hang from the
ceiling using a rubber sucker how big would it have to be?
(Assume a perfect vacuum in
the sucker. Take atmospheric pressure to be 100 000 Pa and use your own weight in
Newtons Take g for the Earth as 10 N/kg).
Assume that the
weight of the pupil is 500 N. (mass = 50 kg)
Force = Pressure x Area so Area =
Force/Pressure = 500/100 000 = 0.005 square metres = 50 square cm.
2. If a second battery is connected in series with the first the current
will get …
larger…
3. If a smaller current flows
through a the lamp the lamp will get …
dimmer…….
4. Which planets move fastest in their
orbits round the Sun, those close to the Sun or those further
away?
……………………
those close to the
Sun………………………………….
5. Why is
this?…………
because the gravitational pull of the Sun
is greatest there……………….
6. Would it be possible for a given
electromagnet to lift a load simply by increasing the current in it? Explain your answer
carefully.
Yes up to a point. There will become a time when the
iron core will be fully magnetised.
7. If an ice cube that is floating in a
glass of water melts the level of water in the glass stays the same. Use that fact to explain
why the effect of global warming is more important on the Antarctic ice cap than the Artic
ice.
The Arctic ice cap is already floating and if it was to
melt the rise in sea level would be quite small. It would actually be zero if the icebergs
were floating in pure water and not in salty water. However the Antarctic ice cap is on
land and if it melted there would be a considerable rise in the sea level.
8. When white light enters a prism at an angle the red light is bent
…
less than.. than the blue light.
9. A
car accelerates steadily from 15 m/s to 25 m/s in 5 s.
(a) what is the average speed of
the car?
(b) what is the acceleration of the car?
(a)
Average speed = {25=15]/2 = 40/2 = 20 m/s (b)
Acceleration = change in speed/time = [25 – 15]/5 = 10/5 = 2
m/s210. (a) a metal washer is heated. What happens to the
hole in the centre of the washer?
(b) What would happen if the piston and cylinder in a
car engine were made of metals that expanded by different amounts when
heated?
(a) the hole gets bigger – very part of the metal
expands but the outer parts of the washer expand more than those nearer the
centre (b) the engine would either seize up or
the pistons would become loose in their cylinders
