All High School Physics Resources
Example Questions
Example Question #45 : Forces
A ball falls off a cliff. What is the force of gravity on the ball?
We need to know the time the ball is in the air in order to solve
We need to know the height of the cliff in order to solve
Newton's second law states:
In this case the acceleration will be the constant acceleration due to gravity on Earth.
Use the acceleration of gravity and the mass of the ball to solve for the force on the ball.
The answer is negative because the force is directed downward. Since gravity is always acting downward, a force due to gravity will always be negative.
Example Question #45 : Forces
An astronaut weighs on Earth. On a distant moon, she weighs . What is the acceleration due to gravity on this moon?
First we need to find the mass of the astronaut using Newton's second law.
We know the total weight of the astronaut and the acceleration due to gravity on Earth, allowing us to solve for her mass.
Now that we know her mass, we can look at her weight on the distant moon. We know her weight and mass, allowing us to solve for the acceleration due to gravity in this new environment.
Example Question #12 : Understanding Gravity And Weight
The mass of the moon is less than that of Earth, causing it to have a gravitational acceleration less than . Which of the following could be the weight of an object on the moon, if the object weighs on Earth?
Newton's second law states that:
We know from the problem that the acceleration due to gravity on the moon is less than the acceleration due to gravity on Earth. The mass of the object, however, will remain constant. The result is that the force of gravity on the object while on the moon will be less than the force on the object while on Earth.
This means that the weight of the object while on the moon must be less than . Since the object has a weight on Earth, however, we know that its weight on the moon cannot be zero. This would imply that either the acceleration due to gravity on the moon is zero, or that the mass is zero, neither of which is possible. This allows us to eliminate from the answers.
The only other option that is less than is .
Example Question #51 : Forces
An astronaut has a mass of and Mars has an acceleration due to gravity of . What is her weight on Mars?
Weight is a very specific force, determined by the acceleration due to gravity acting on a given mass. Using Newton's second law, we can see that weight will be equal to the equation:
We are given the mass of the astronaut and the acceleration due to gravity on Mars. Using these values, we can calculate her weight on Mars.
Example Question #1 : Universal Gravitation
Two satellites in space, each with a mass of , are apart from each other. What is the force of gravity between them?
To solve this problem, use Newton's law of universal gravitation:
We are given the constant, as well as the satellite masses and distance (radius). Using these values we can solve for the force.
Example Question #604 : Newtonian Mechanics
Two satellites in space, each with a mass of , are apart from each other. What is the force of gravity between them?
To solve this problem, use Newton's law of universal gravitation:
We are given the constant, as well as the satellite masses and distance (radius). Using these values we can solve for the force.
Example Question #1 : Universal Gravitation
Two asteroids in space are in close proximity to each other. Each has a mass of . If they are apart, what is the gravitational force between them?
To solve this problem, use Newton's law of universal gravitation:
We are given the constant, as well as the asteroid masses and distance (radius). Using these values we can solve for the force.
Example Question #2 : Universal Gravitation
Two asteroids in space are in close proximity to each other. Each has a mass of . If they are apart, what is the gravitational acceleration that they experience?
Given that , we already know the mass, but we need to find the force in order to solve for the acceleration.
To solve this problem, use Newton's law of universal gravitation:
We are given the constant, as well as the satellite masses and distance (radius). Using these values we can solve for the force.
Now we have values for both the mass and the force, allowing us to solve for the acceleration.
Example Question #2 : Universal Gravitation
Two asteroids, one with a mass of and the other with mass , are apart. What is the gravitational force on the LARGER asteroid?
To solve this problem, use Newton's law of universal gravitation:
We are given the constant, as well as the asteroid masses and distance (radius). Using these values we can solve for the force.
It actually doesn't matter which asteroid we're looking at; the gravitational force will be the same. This makes sense because Newton's 3rd law states that the force one asteroid exerts on the other is equal in magnitude, but opposite in direction, to the force the other asteroid exerts on it.
Example Question #3 : Universal Gravitation
Two asteroids, one with a mass of and the other with mass are apart. What is the gravitational force on the SMALLER asteroid?
To solve this problem, use Newton's law of universal gravitation:
We are given the constant, as well as the asteroid masses and distance (radius). Using these values we can solve for the force.
It actually doesn't matter which asteroid we're looking at; the gravitational force will be the same. This makes sense because Newton's 3rd law states that the force one asteroid exerts on the other is equal in magnitude, but opposite in direction, to the force the other asteroid exerts on it.