How Can I Ace My Physics Test on Newton's Laws and Gravitation?

In summary, to achieve a 100 percent on your upcoming physics test on Newton's 3 laws and universal law of gravitation, it is important to do lots of practice problems and master the art of drawing free body diagrams. It is also important to understand the differences between Newton's 1, 2, and 3 laws. Additionally, for proportionality problems in Newton's law of gravitation, remember that weight varies linearly with the planet's mass and inversely with the square of its radius. Good luck on your test!
  • #1
Ameer Bux
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Hi guys. I am planning to get 100 percent for my upcoming physics test in two days time. I am i grade 11. The test is based on Newtons 3 laws and universal law of gravitation.

What are some of the best tips you can offer from your experience to help me achieve my goal?
 
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  • #2
Ameer Bux said:
Hi guys. I am planning to get 100 percent for my upcoming physics test in two days time. I am i grade 11. The test is based on Newtons 3 laws and universal law of gravitation.

What are some of the best tips you can offer from your experience to help me achieve my goal?
Do lots of practice problems. :smile:
 
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  • #3
Ameer Bux said:
Hi guys. I am planning to get 100 percent for my upcoming physics test in two days time. I am i grade 11. The test is based on Newtons 3 laws and universal law of gravitation.

What are some of the best tips you can offer from your experience to help me achieve my goal?
> master the art of drawing free body diagrams
> identify all forces acting in that diagram and apply Newton 1 for bodies in equilibrium (at rest or moving at constant velocity) or Newton 2 for accelerating bodies, with the wisdom to know the difference
> Do not confuse Newton 3 with Newton 1 or Newton 2. Newton 3 refers to equal and opposite forces acting on different bodies, whereas Newton 1 and 2 refer to net forces acting on the same body.

(I like your Avitar. Sort of like "Now that my house has burned down, I have a better view of the moon").
 
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  • #4
berkeman said:
Do lots of practice problems. :smile:
Did 40 problems so far on Newtons first 3 laws. Going to start with universal law of gravitation in 30 mins.
 
  • #5
PhanthomJay said:
> master the art of drawing free body diagrams
> identify all forces acting in that diagram and apply Newton 1 for bodies in equilibrium (at rest or moving at constant velocity) or Newton 2 for accelerating bodies, with the wisdom to know the difference
> Do not confuse Newton 3 with Newton 1 or Newton 2. Newton 3 refers to equal and opposite forces acting on different bodies, whereas Newton 1 and 2 refer to net forces acting on the same body.

(I like your Avitar. Sort of like "Now that my house has burned down, I have a better view of the moon").
Thanks a lot. Do you guys know a quick way to solve a proportionality problem in Newtons law of gravitation? I need some steps/method to follow. I don't know how to approach these kind of problems.

Example of a problem like that is as follows : A large planet has a radius 10x that of the Earth and a mass of 300x that of the earth.
a.) if the weight of a body is 500N on Earth what will be the weight on this planet?
b.) compare strenght of gravitational fields at the surface of the 2 planets.
 
  • #6
The weight of an object on the surface of a particular planet is GmM/r^2, where G is the universal gravitational constant, m is the mass of the object, M is the mass of the planet, and r is the radius of the planet. So weight varies directly linearly with the planet mass, and inversely as the square of its radius. So in comparison to earth, if the planet mass increases 300 fold, and the planet's radius increases by 10 fold, then the object's weight increases by 300/10^2 = 300/100, that is, by a factor of 3. So the 500 N body weight on Earth will weigh 1500 N on that planet. So the gravitational field increases by 3.

You should note that since Weight = mg, then using the above formula yields g = GM/r^2, which , on planet earth, works out to g = 9.8 m/s^2, the acceleration of gravity. On the massive planet, g would be 9.8(3) or 29.4 m/s^2.
 

FAQ: How Can I Ace My Physics Test on Newton's Laws and Gravitation?

1. What are Newton's Laws of Motion?

Newton's Laws of Motion are a set of three physical laws that describe the relationships between the forces acting on an object and its motion.

2. What is the first law of motion?

The first law of motion, also known as the law of inertia, states that an object at rest will remain at rest and an object in motion will remain in motion at a constant velocity unless acted upon by an external force.

3. How do you apply Newton's second law of motion?

Newtown's second law of motion states that force is equal to mass times acceleration. This means that the greater the mass of an object, the more force is needed to accelerate it.

4. What is an example of Newton's third law of motion?

Newton's third law of motion states that for every action, there is an equal and opposite reaction. An example of this is when a person jumps off a boat onto a dock, the force of the person's feet pushing off the boat causes an equal and opposite force of the boat pushing back.

5. How can understanding Newton's laws of motion be useful in everyday life?

Understanding Newton's laws of motion can be useful in everyday life for activities such as driving a car, playing sports, and even simply walking. By understanding these laws, we can better predict and control the motion of objects and ourselves, making our daily tasks and activities easier and more efficient.

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