### Tutorial 1

1. A rock of mass 2000kg is placed 340m from another rock of mass 5400kg.
1.1. State Newton's Law of Universal Gravitation as an equation.
1.1.
1.2. Calculate the magnitude of the gravitational force of attraction between the rocks.
1.2.

1.3. What is the nature of the force?
1.3. attractive
Gravitational forces are always attractive.
1.4. What would happen to the size of these forces if the objects were moved closer?
1.4.
The sizes would increase.
inverse proportion

2. The gravitational force of attraction between two objects X and Y,
is 2 x 10-4N. The mass X is 2300kg and that of Y is 9890kg.

2.1. Determine the distance between their centres.
2.1.
2.2. What would happen to the magnitude of the forces if the distance was increased?
2.2. The forces would decrease.
inverse proportion

3. The gravitational force of attraction between two masses P and T,
is 5 x 10-2 N. If the mass of P is 70kg and the distance between them is 200cm, calculate the mass of T.

3. Convert the 200cm to 2m.
(divide by 100)

4. What is the name for the force with which the Earth attracts an object?
A. gravity
B. weight
C. mass
D. inertia
4.
B. weight
Weight is a force.

5. Halley's comet, of approximate mass 1 x 1015 kg was 1,3 x 108 km from the Earth's center, at it's closest approach during it's last sighting in 1986.

5.1. Name the force via which the Earth and the comet interact.
5.1. gravitational force
5.2. Is the magnitude of the force experienced by the comet the same, greater than or less than the force experienced by the Earth? Explain, using a specific law of physics.
5.2. the same
This is because of Newton's Third Law of Action and Reaction.
5.3. Does the acceleration of the comet increase, decrease of remain the same as it moves closer to the Earth. Explain.
5.3. increase
The force increases as it gets closer to the Earth. From Newton's Second Law, the acceleration must increase.
5.4. Determine the distance between the Earth and Halley's Comet in meters.
5.4. To convert km to m you must multiply by 1000 or 103.
5.5. If the mass of the Earth is 5,98 x 1024 kg, calculate the magnitude of the force exerted by the Earth on Halley's comet at it's point of closest approach.
5.4.

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