Physical Science Lesson 3 and Quiz 3

The strength of the gravitational force does/does not depend on whether the ball is going up or down.

does not

g

the symbol representing the acceleration caused by gravity. It is equal to 22 mi/hour per second or 32 ft/second per second or 9.8 m/second per second depending on the units. g is constant.

Law of Gravity

Every object in the universe attracts every other object by a long-range gravitational interaction that obeys Newton's third law. The strength of the attractive force, F, varies with the masses, M and m, of the two objects and the distance, d, between their centers according to the relationship

c. The force decreases when the distance is d2 When the masses remain the same but the distance between the masses increases, the gravitational force decreases.

If d22 is twice as large as d1, how is the force different? a. In both situations, the force remains the same. b. The force increases when the distance is d22. c. The force decreases when the distance is d2

e. 1, 3, 2 The gravitational force is most evident when at least one of the two objects is very massive (for example, when one of the objects is the Earth). When one of the objects is planet-sized, the gravitational force on an object due to the planet is called the object's weight. As you read in the textbook, scientists have been able to measure the very small attraction even between people-sized objects, but this gravitational attraction is not called weight.

Rank the pictures in order of most gravitational force to least gravitational force. a. 1, 2, 3 b. 2, 3, 1 c. 3, 2, 1 d. 3, 1, 2 e. 1, 3, 2 f. 2, 1, 3

Suppose I drop a rock the same time a ball which was dropped from above passes the rock. (Someone a few meters above you drops a ball. When that ball is even with your hand, you let go of the rock you're holding.) Which will hit the ground first? a. The ball will hit the ground first. b. The rock will hit the ground first. c. The rock and ball hit at the same time.

The ball will hit the ground first.

The next three questions, Questions 2 - 4, relate to a cannon ball and a marble that are dropped from the same height at the same time. Both are originally at rest. Ignore air friction. How does the gravitational force on the cannonball compare with that on the marble? Select one: a. The gravitational force on the cannonball is larger. b. The gravitational force on the cannonball is smaller. c. The gravitational force on the cannon ball is the same as the force on the marble.

The gravitational force on the cannonball is larger.

Let's apply Newton's laws and his Universal Law of Gravitation to see what we can learn about the gravitational force and how it changes on the Earth's moon. The moon has a mass of about 1/80 of the Earth's and a radius about 1/4 of the Earth's. 1. What is the mass of an object, say an apple, on the moon compared to the mass of the same apple on the earth? a. The mass of an object is the same on the moon and on the earth. b. The mass of the object is greater on the moon. c. The mass of the object is greater on the earth.

The mass of an object is the same on the moon and on the earth

Suppose I drop a rock the same time a ball which was dropped from above passes the rock. (Someone a few meters above you drops a ball. When that ball is even with your hand, you let go of the rock you're holding.) What would you say about the accelerations of the two objects? a. The ball has a greater acceleration than the rock. b. The rock has a greater acceleration than the ball. c. The rock and ball have the same acceleration.

The rock and ball have the same acceleration.

The next three questions, Questions 2 - 4, relate to a cannon ball and a marble that are dropped from the same height at the same time. Both are originally at rest. Ignore air friction. How do the speed and acceleration of the cannonball compare with those of the marble at any given time after they are dropped? Select one: a. The speed and acceleration of the cannonball are both greater than those of the marble. b. The speed and acceleration of the cannonball are both smaller than those of the marble. c. The speed and acceleration of the cannonball are both the same as those of the marble. d. The speed of the cannonball is the same, but the acceleration is larger. e. The acceleration of the cannonball is the same, but the speed is larger.

The speed and acceleration of the cannonball are both the same as those of the marble.

b. The force increases. When the distance remains the same but the masses increase, the gravitational force increases. Without changing either of the masses, how could you make the force the same as it was initially? If you thought that you could increase the distance between the two masses, you would be correct.

What happens if the masses change? Look at the next diagram. If d22 is equal to d11, but m22 is twice as large as m11, how is the force different? a. The force remains the same. b. The force increases. c. The force decreases.

The next three questions, Questions 2 - 4, relate to a cannon ball and a marble that are dropped from the same height at the same time. Both are originally at rest. Ignore air friction. Which is easier to accelerate? Select one: a. The cannonball requires more force to accelerate it as much as the marble. b. The cannonball requires less force to accelerate it as much as the marble. c. The cannon ball and the marble will accelerate the same amount in response to the same force.

a. The cannonball requires more force to accelerate it as much as the marble.

Two objects are attracted to each other by gravitational forces. Suppose I double the mass of one of the objects. This changes the gravitational forces between them. I can make this force the same as it was at first, however, by Select one: a. increasing the distance between the two objects. b. decreasing the distance between the two objects. c. increasing the mass of the other object. d. doing nothing--the force is not changed unless I change the mass of both objects, since the gravitational force depends on both these masses. e. decreasing the distance between the objects and increasing the mass of the other object.

a. increasing the distance between the two objects.

All objects weigh less near the surface of the moon than the same objects weigh near the surface of the earth. This is because Select one: a. the moon has less mass than the earth. b. the moon has a smaller radius than the earth. c. there is less air on the moon's surface. d. the universal gravitational constant is smaller near the moon. e. the buoyant force on the moon is greater than on earth.

a. the moon has less mass than the earth.

What is the acceleration due to gravity of the apple when on the moon compared to the acceleration due to gravity of the same apple when it is on the earth? a. The acceleration of the apple on the moon is larger than the acceleration of the apple on the earth. b. The acceleration of the apple is the same whether on the moon or on the earth. c. The acceleration of the apple on the moon is smaller than the acceleration of the apple on the earth.

c. The acceleration of the apple on the moon is smaller than the acceleration of the apple on the earth.

What is the relative strength of the gravitational force on the apple when it is on the moon compared to the gravitational force on that same apple when it is on the earth? a. The gravitational force on the apple due to the moon is larger than the gravitational force on the apple due to the earth. b. The gravitational force on the apple is the same strength whether on the moon or on the earth. c. The gravitational force on the apple due to the moon is smaller than the gravitational force on the apple due to the earth.

c. The gravitational force on the apple due to the moon is smaller than the gravitational force on the apple due to the earth.

As a body moves higher and higher above the surface of the earth, Select one: a. its weight increases. b. its mass increases. c. its weight decreases. d. its mass decreases. e. both its weight and its mass decrease.

c. its weight decreases.

The acceleration and force of gravity are ____ for any given object as it falls

constant

Two balls positioned at the same height, with one dropped at the same instant as the second ball is thrown horizontally, will hit the ground at the same time/at different times

same time because the downward acceleration on both is the same