1. A gardener fits a hanging basket up on their patio. The force of gravity is 240 newtons. The baskets perpendicular distance from the pivot is 0.5 metres.
a) Calculate the moment produced by the weight of the hanging basket by the weight of the hanging basket.
b) What does moment mean in this context?
2. Neptune is the furthest planet away from the Sun and has 13 moons spinning around it. Four of its largest are in the table below.
a) A centripetal force is acting on each of these moons. What provides this centripetal force?
b) What relationship, if any, is there between the distance a moon is from Neptune and the time it take to orbit Neptune.
c) Astronomers have more data about the Neptune moons due to more powerful telescopes. Suggest another reason why.
|
Name |
Diameter (km) |
Average distance from Neptune (km) |
Length of time to complete an orbit |
|
Triton |
2707 |
354, 800 |
5 days, 21 hours |
|
Proteus |
418 |
117, 647 |
1 day, 3 hours |
|
Nereid |
340 |
5, 513, 400 |
360 days, 3 hours |
|
Larissa |
195 |
73, 548 |
13 hours, 19 minutes |
3. 
Our Solar System is composed of eight planets. Five of them are listed in the table below.
|
Name |
Diameter (km) |
Distance from Sun (millions of km) |
Period (days) |
|
Mercury |
4, 840 |
58 |
87 |
|
Earth |
12, 760 |
149 |
365 |
|
Jupiter |
142, 800 |
778 |
4, 332 |
|
Saturn |
119, 400 |
1, 428 |
10, 759 |
|
Neptune |
48, 400 |
4, 497 |
60, 190 |
a) What’s the name of the galaxy which contains the Solar System?
b) Explain what’s meant by a planet’s period?
c) Is there a relationship between the distance a planet is from the Sun and it’s period? If yes, explain what.
d) What, if any, is the relationship between the diameter of a planet and its period?
4. A tractor must be built so that it doesn’t topple over easily in the uneven ground of the fields.
a) What’s meant by the centre of gravity of a tractor?
b) Explain why a stable tractor doesn’t topple by using the terms ‘resultant moment’ and ‘line of action of the weight’.
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ANSWERS
1. a) 240 x 0.5 = 120 newton metres (Nm)
b) Turning effect
2. a) Neptune’s gravitational pull.
b) As the distance from Neptune increases, the time taking to orbit increases. There’s a positive correlation.
c) Answers include:
– Computers are able to process the data.
– There are telescopes in space.
– Instruments other than optical telescopes are now available.
3. a) The Milky Way
b) The time taken for a planet to orbit the Sun.
c) The greater the distance from the Sun the greater the planet’s period.
d) There’s no relationship.
4. a) The point at which the total mass seems to act or appears to be concentrated.
b)The line of action of the weight of the tractor lies inside the base. The resultant moment returns the tractor to its original position.