Newton's Law and Gravity Lecture Tutorial (Astronomy Midterm)

2. Do you disagree with either or both of the students? Explain your reasoning.

I agree with Student 1, Newton's third law states that each force exerts the same strength in opposite directions.

8. Do you agree or disagree with either or bother of the students? Explain your reasoning.

I agree with Student 2, because combined mass determines the amount of force.

4. On the diagram, clearly label the location where the space probe would be when the gravitational force by Earth on the space probe is the strongest? Explain your reasoning.

Closest to Earth. The closer that the probe is, the more gravitational force that Earth will exert on it.

5. On the diagram, clearly label the location where the space probe would be when the gravitational force by Mars on the space probe is the strongest. Explain your reasoning.

Closest to Mars. The closer the probe is, the more gravitational force from Mars that is being exerted on it.

11. Your weight on Earth is simply the gravitational force between you and Earth. Would your weight be more, less, or the same on Mars? Explain your reasoning.

Less, Mars has a smaller mass, weight is in relation to mass with gravity being an additional factor.

6. Where would space probe experience the strongest net (or total) gravitational force exerted on it by Earth and Mars? Explain your reasoning.

On Earth, because Earth's mass is larger and gravitational force on objects is a result of combined mass.

1. Given that Earth is much larger and more massive than the Moon, how does the strength of the gravitational force that the Moon exerts on Earth compare to the gravitational force that Earth exerts on the Moon? Explain your reasoning.

The force that they both exert on each other is equal, it follows Newton's third law that every action has an equal and opposite reaction, or every force is met with an equal and opposite force.

7. When the spacecraft is at the halfway point, how does the strength of the gravitational force on the space probe by Earth compare with the strength of the gravitational force on the space probe by Mars? Explain your reasoning.

The gravitational force exerted by Earth is still greater due to its combined mass with the space probe.

10. Imagine that you need to completely stop the motion of the space probe and have it remain at rest while you perform a shutdown and restart procedure. You have decided that the best place to carry out this procedure would be at the position where the net (or total) gravitational force on the space probe by Mars and Earth would be zero. On the diagram, label the location where you would perform this procedure. Explain the reasoning behind your choice.

The middle is the only place where one gravitational force doesn't outweigh the other.

3. How would the strength of the force between the Moon and Earth change if the mass of the Moon were somehow made two times greater than its actual mass?

The strength would not change, it remains equal and opposite.

9. If the space probe had lost all ability to control its motion and was sitting at rest at the midpoint between Earth and Mars, would the spacecraft stay at the midpoint or would it start to move? If you think it stays at the midpoint, explain why it would not move. If you think it would move then (a) Describe the direction is would move; (b) describe if it would speed up or slow down; (c) describe how the net (or total) force on the space probe would change during this motion; and (d) identify when/where the space probe would experience the greatest acceleration.

a) It would move toward Earth. b) It would speed up if Earth's force is pulling it. c) Earth would have the greater force due to its larger combined mass with the probe. d) The space probe would experience the greatest acceleration when it's closest to Earth.