# Gravity Unit Test

1. On which object will Earth’s gravity act with the greatest magnitude?

A. a toaster
B. a television
C. a piano***
D. a banana

2. Why does a beach ball weigh less than a bowling ball?

A. The beach ball pushes harder against Earth.
B. The beach ball has more air.
C. The beach ball has more mass.
D. The beach ball is less strongly attracted to Earth.***

3. Which statement about gravitational attraction is correct?

A. All objects on Earth experience the same gravitational attraction.
B. All objects with mass experience gravitational attraction.***
C. Objects with greater volume have a greater gravitational attraction.
D. Objects in space will not have any gravitational attraction.

4. Use the table to answer the question.
Planet | Estimated Mass of Planet(10kg)
Venus | 4.87
Mars | 0.642
Jupiter | 1,898.0
Neptune| 102.0

A spacecraft flies within 500,000 km of each of these planets. Based on its mass, which planet would gravitationally attract the spacecraft the least?

A. Venus
B. Jupiter
C. Neptune
D. Mars***

5. A student conducts an investigation to study the effect of gravity on objects of different masses. Which step should be first in the investigation?

A. Time how long it takes for the objects to fall.
B. Find objects of different masses and measure them.***
C. Drop the objects from a height.
D. Measure the distance between the objects.

6. A science class is conducting an investigation to see how gravity affects objects of different masses. They drop three balls from the same height. They time how long it takes the balls to hit the ground. What are the students comparing?

A. the gravitational attraction of each ball
B. the mass of each ball
C. the height from which each ball is dropped
D. the time it takes for each ball to fall***

7. A hammer and a feather are dropped from the same height. Imagine that there is no resistance to the object's motion in the air. Which value will be different for the two objects?

A. the gravitational attraction between the Earth and the objects***
B. the time it takes for them to fall
C. the velocity of the objects
D. the upward push of air resistance

8. A coin (5 grams), a small parachute (21 grams), and a hammer
(710 grams) are all dropped from a height of 10 meters. The coin and the hammer take about the same amount of time to fall. Which statement describes the time it takes for the parachute to fall?

A. It takes the same amount of time to fall because the effect of gravity is the same.
B. It takes less time to fall because it has the least mass.
C. It takes longer to fall because it experiences greater air resistance.***
D. It takes less time to fall because it has the most surface area.

9. Which object would have the slowest speed at terminal velocity?

A. a 50-kilogram block with no parachute
B. a 10-kilogram block with a small parachute
C. a 10-kilogram block with no parachute
D. a 50-kilogram block with a large parachute***

10. How does an open parachute slow a skydiver’s fall?

A. The parachute changes the mass of the skydiver.
B. The parachute weakens the force of gravity.
C. The parachute pulls the skydiver up.
D. The parachute increases the force opposing gravity.***

11. A science class is planning an investigation about gravity and objects on Earth. In three to four sentences, explain the steps the class should take to provide data to help them make a conclusion about the effect of gravity on objects of different masses. (4 points)

12. Two skydivers of different masses jump from a plane. In three to five sentences, explain how their falls compare, including the effects of gravity, mass, and air resistance. (4 points)

## Note: Answers may vary for questions 11 and 12 as they require written responses. The given answers are example responses.

11. To provide data for their investigation, the science class should first find objects of different masses and measure them. Then, they should drop the objects from a height and time how long it takes for them to fall. After gathering data, they can compare the times it took for the different objects to fall and make a conclusion about the effect of gravity on objects of different masses.

12. The skydiver with the greater mass will experience a greater gravitational force and will fall faster than the skydiver with the lesser mass. However, both skydivers will eventually reach terminal velocity, where the force of air resistance will balance the force of gravity and they will fall at a constant speed. The skydiver with the higher mass will require more air resistance to balance the force of gravity, so they may require a larger parachute or more surface area to slow their fall compared to the lighter skydiver.

## 1. On which object will Earth’s gravity act with the greatest magnitude?

C. a piano

Because pianos are notorious for being heavy, especially when you have to move them up or down a flight of stairs.

2. Why does a beach ball weigh less than a bowling ball?

D. The beach ball is less strongly attracted to Earth.

It's because beach balls are known for their laid-back, carefree attitude. They just don't take gravity very seriously.

3. Which statement about gravitational attraction is correct?

B. All objects with mass experience gravitational attraction.

Even in the vastness of space, where nobody can hear you scream, gravity still finds a way to pull objects together.

4. Use the table to answer the question.
Planet | Estimated Mass of Planet(10kg)
Venus | 4.87
Mars | 0.642
Jupiter | 1,898.0
Neptune| 102.0

A spacecraft flies within 500,000 km of each of these planets. Based on its mass, which planet would gravitationally attract the spacecraft the least?

D. Mars

Mars might be known as the "Red Planet," but it's not red hot when it comes to gravitational attraction. It's more like a lukewarm planet.

5. A student conducts an investigation to study the effect of gravity on objects of different masses. Which step should be first in the investigation?

B. Find objects of different masses and measure them.

Can't study the effect of gravity on objects of different masses without the objects, right? It's like a magician pulling a rabbit out of a hat - you need the rabbit first.

6. A science class is conducting an investigation to see how gravity affects objects of different masses. They drop three balls from the same height. They time how long it takes the balls to hit the ground. What are the students comparing?

D. the time it takes for each ball to fall

They're basically racing the balls to the ground. It's like a gravity Olympics, but without the torch or the elaborate opening ceremony.

7. A hammer and a feather are dropped from the same height. Imagine that there is no resistance to the object's motion in the air. Which value will be different for the two objects?

A. the gravitational attraction between the Earth and the objects

The feather, being light and fluffy, won't have the same gravitational attraction as the hammer. It's like comparing a sumo wrestler to a featherweight boxer. The sumo wrestler would definitely have a greater gravitational attraction.

8. A coin (5 grams), a small parachute (21 grams), and a hammer (710 grams) are all dropped from a height of 10 meters. The coin and the hammer take about the same amount of time to fall. Which statement describes the time it takes for the parachute to fall?

C. It takes longer to fall because it experiences greater air resistance.

The parachute is like a superhero cape, slowing down the fall and defying gravity like a boss. It's like the gravity version of a Netflix binge-watch, stretching out the fun for as long as possible.

9. Which object would have the slowest speed at terminal velocity?

D. a 50-kilogram block with a large parachute

The large parachute acts like a break, slowing down the block's fall. It's like taking a turtle to a race and strapping a rocket onto it. It's not going to win any speed awards.

10. How does an open parachute slow a skydiver’s fall?

D. The parachute increases the force opposing gravity.

The parachute is like a superhero sidekick come to the rescue. It creates an opposing force to gravity, making the skydiver feel like they're floating on a cloud. It's like having your own personal gravity-defying assistant.

11. A science class is planning an investigation about gravity and objects on Earth. In three to four sentences, explain the steps the class should take to provide data to help them make a conclusion about the effect of gravity on objects of different masses.

The class should start by gathering objects of different masses, ranging from light to heavy. Then, they should drop each object from the same height and time how long it takes for each object to hit the ground. They should repeat this process multiple times for each object to ensure accurate data. Finally, they should analyze the results and look for any patterns or trends that indicate how gravity affects objects of different masses. It's like conducting a scientific dance party, but instead of dancing, you're dropping objects.

12. Two skydivers of different masses jump from a plane. In three to five sentences, explain how their falls compare, including the effects of gravity, mass, and air resistance.

The skydiver with a greater mass will experience a stronger gravitational pull compared to the skydiver with a lighter mass. This means that the heavier skydiver will accelerate faster towards the ground. However, both skydivers will eventually reach terminal velocity, the point where the force of gravity is balanced by air resistance. At this point, both skydivers will fall at a constant speed, regardless of their mass. It's like a skydiving battle: heavyweight vs. lightweight, but they both end up floating peacefully in the air.

## 11. Steps to provide data for the investigation on the effect of gravity on objects of different masses:

1. Gather objects of different masses, such as balls or blocks, and measure their masses using a scale.
2. Create a controlled environment by conducting the experiment indoors or in an area free from wind and air currents.
3. Drop the objects from the same height and measure the time it takes for each object to fall using a stopwatch.
4. Repeat the experiment multiple times for each object and calculate the average time for each object to fall.
5. Analyze the data by comparing the time taken for each object to fall. Determine if there is any relationship between the mass of the object and the time it takes to fall, which will indicate the effect of gravity on objects of different masses.

12. When two skydivers of different masses jump from a plane, the effects of gravity, mass, and air resistance come into play. Gravity pulls both skydivers downwards at the same rate, as mass does not affect the strength of the gravitational force. However, the skydiver with a greater mass experiences a greater force of gravity pulling them downward. As a result, the skydiver with a higher mass falls faster than the skydiver with a lower mass due to the greater force of gravity. Additionally, air resistance plays a role in slowing down the fall of both skydivers. However, the skydiver with a greater mass will experience a relatively greater air resistance due to their larger surface area, which may slightly reduce their speed compared to the skydiver with a lower mass.

## 1. To determine on which object Earth's gravity will act with the greatest magnitude, we need to consider the mass of each object. Gravity is directly proportional to mass, so the greater the mass of an object, the greater the gravitational force it experiences. Looking at the given options, the object with the greatest mass is the piano, so the correct answer is C. a piano.

2. The weight of an object is determined by the gravitational force acting on it. The beach ball weighs less than the bowling ball because it experiences less gravitational force. Gravity pulls objects towards the center of the Earth, and the force of gravity is directly proportional to the mass of the object. The beach ball has less mass compared to the bowling ball, so it is less strongly attracted to Earth. Therefore, the correct answer is D. the beach ball is less strongly attracted to Earth.

3. Gravitational attraction occurs between all objects with mass. This means that all objects, regardless of their mass, experience gravitational attraction. Hence, the correct answer is B. all objects with mass experience gravitational attraction.

4. To determine which planet would gravitationally attract the spacecraft the least, we need to compare the masses of the planets. Based on the given mass values, Mars has the smallest mass among the listed planets. Since gravitational force is directly proportional to mass, the planet with the smallest mass will gravitationally attract the spacecraft the least. Therefore, the correct answer is D. Mars.

5. In the investigation studying the effect of gravity on objects of different masses, the first step should be to find objects of different masses and measure them. This is necessary in order to have objects of known masses to test the effect of gravity on. So, the correct answer is B. Find objects of different masses and measure them.

6. In the investigation where three balls of different masses are dropped from the same height and their falling times are timed, the students are comparing the time it takes for each ball to fall. By measuring and comparing the falling times, the students can observe how gravity affects objects of different masses. Thus, the correct answer is D. the time it takes for each ball to fall.

7. In the scenario where a hammer and a feather are dropped from the same height with no air resistance, the value that will be different for the two objects is the gravitational attraction between the Earth and the objects. While both objects experience the same acceleration due to gravity, the feather will experience less gravitational force compared to the hammer due to its smaller mass. Hence, the correct answer is A. the gravitational attraction between the Earth and the objects.

8. In the given scenario where a coin, a small parachute, and a hammer are dropped from a height of 10 meters, the statement that describes the time it takes for the parachute to fall is that it takes longer to fall because it experiences greater air resistance. The parachute has a larger surface area compared to the coin and the hammer, leading to increased air resistance. This causes the parachute to fall slower than the other objects. Hence, the correct answer is C. It takes longer to fall because it experiences greater air resistance.

9. Terminal velocity refers to the constant velocity reached by a falling object when the drag force of the air resistance equals the gravitational force acting on the object. In this case, the object with the largest parachute (the 50-kilogram block with a large parachute) will have the slowest speed at terminal velocity. The larger parachute increases the drag force, reducing the acceleration and ultimately leading to a slower speed at terminal velocity. Therefore, the correct answer is D. a 50-kilogram block with a large parachute.

10. An open parachute slows a skydiver's fall by increasing the force opposing gravity. When a parachute opens, it creates a large surface area that interacts with the air molecules, generating a significant amount of air resistance. The upward force due to air resistance counteracts the downward force of gravity, slowing down the skydiver's descent. Hence, the correct answer is D. the parachute increases the force opposing gravity.

11. In order to provide data to help them make a conclusion about the effect of gravity on objects of different masses, the science class should follow these steps:

1. Select objects of different masses, such as balls or blocks, and measure their masses accurately using a balance.
2. Design an experiment where each object is dropped from the same height, ensuring that the height is consistent for all trials.
3. Time how long it takes for each object to fall using a stopwatch or a timer.
4. Repeat the experiment multiple times for each object to ensure accuracy and reliability of the data.
5. Analyze the data collected, comparing the falling times of each object. The objects with greater mass should take longer to fall compared to objects with lesser mass, demonstrating the effect of gravity on objects of different masses.

12. When two skydivers of different masses jump from a plane, their falls compare as follows:

The skydiver with a greater mass will experience more gravitational force compared to the skydiver with a lesser mass. Gravity pulls both skydivers downwards, causing them to accelerate towards the ground. Since gravitational force is directly proportional to mass, the skydiver with greater mass will experience a greater downward force and accelerate at a faster rate.

However, the skydiver with a greater mass will also experience more air resistance due to their larger surface area. Air resistance opposes the motion of the falling objects, and it increases with the surface area and speed of the object. As a result, the skydiver with greater mass will experience a stronger opposing force from air resistance.

These combined effects of gravity and air resistance result in a slower overall fall for the skydiver with a greater mass compared to the skydiver with a lesser mass. The skydiver with lesser mass will experience less gravitational force and encounter less air resistance, allowing them to fall at a faster rate.