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```					                                     SUCCESS ACADEMY LESSON 7

1. Go to http://www.williamsclass.com/EighthScienceWork/Gravity.htm
and take notes on factors which affect gravitational force. (at least 10 facts)

2.     Complete the following gizmo:

Student Exploration: Weight and Mass
http://www.explorelearning.com/index.cfm?method=cResource.dspDetail&ResourceID=653
Big Idea 13: Forces and Changes in Motion
Benchmark: SC.6.P.13.1 Investigate and describe types of forces including contact forces and forces acting at
a distance, such as electrical, magnetic, and gravitational. (Also assesses SC.6.P.13.2 and SC.8.P.8.2.)

Vocabulary: balance, force, gravity, mass, newton, spring scale, weight

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

1. Your weight is the pull of gravity on your body. Suppose you step on a bathroom scale on the Moon. How
would your weight on the Moon compare to your weight on Earth?

A. greater on the Moon       B. less on the Moon       C. same on Earth and the Moon

2. Your mass is the amount of matter, or “stuff,” in your body. How would your mass on the Moon compare to

A. greater on the Moon       B. less on the Moon       C. same on Earth and the Moon

Gizmo Warm-up
On the Weight and Mass Gizmo™, you can use a balance to compare
the masses of objects.

1. Place the dog on the right pan of the balance. What happens?

_____________________________

2. Place the 5-kilogram (kg) mass on the other pan. Which has more
mass, the dog or the 5-kg mass?

__________________________________________

3. The 5-kg mass is heavier than the dog, so take it off the pan and place a 1-kg mass on the pan. Add 1-kg
masses to the left pan until it goes down. Then take one of the 1-kg masses off the pan so that the masses
are above the dog.

4. Use this process of adding and subtracting other masses from the left pan until the two pans are balanced.
Add up all the masses on the left pan. This is equal to the mass of the dog.

What is the mass of the dog? _________________________________________________
Activity A:            Get the Gizmo ready:
Weight on                  Click Clear scales to remove all objects from the
different planets           spring scale and the balance.

Introduction: A spring scale is used to measure force. Since weight is a type of force, a spring scale can
measure weight. The metric unit of force is the newton (N).

Question: Will an object’s weight change on different planets?

1. Measure: Place the pumpkin on the spring scale. Move the cursor over the red line on the scale to see its
weight measured to the nearest newton.

What is the weight of the pumpkin? _____________________________________________

2. Predict: If you take an object to a different planet, do you think its weight will stay the same or be different?

Same                   Different

3. Collect data: Measure the weights of the following objects on Earth, the Moon, Mars, and Jupiter. Record
your measurements in the data table below.

Pumpkin                    Dog                 Watermelon
Weight on Earth
Weight on Moon
Weight on Mars
Weight on Jupiter

4. Analyze: Does the weight of an object change when it is moved to a different planet?

_________________________________________________________________________

5. Extend your thinking: Which celestial body had the strongest gravity, Earth, the Moon, Mars, or Jupiter?

Explain how you know. _____________________________________________

_____________________________________________________________________________________

_____________________________________________________________

_________________________________________________________________________
Activity B:
Mass on different
 Click Clear scales.
planets

Question: How do weight and mass change on different planets?

1. Predict: If you take an object to a different planet, do you think its mass will stay the same or be different?

Same                   Different

2. Collect data: Use the balance to measure the masses of the following objects on Earth, the Moon, Mars,
and Jupiter. Record your measurements in the data table below.

Pumpkin                    Dog                Watermelon
Mass on Earth
Mass on Moon
Mass on Mars
Mass on Jupiter

3. Analyze: Does the mass of an object change when it is moved to a different planet?

_________________________________________________________________________

4. Draw conclusions: Based on what you have learned about mass and weight, why do you think the mass

did not change but the weight did? _________________________________

_________________________________________________________________________

_________________________________________________________________________

_________________________________________________________________________

5. Extend your thinking: First, using the balance, find the mass of a pumpkin on Jupiter. Then place the
pumpkin on the spring scale and record its weight. Finally remove the pumpkin and weigh the masses from
the balance on the spring scale. How do the weights compare?

_________________________________________________________________________

_________________________________________________________________________
ASSESSMENT

Multiple Choice
Identify the choice that best completes the statement or answers the question.

1. Some forces require direct contact, while others, like gravity, act at a distance. Which of the
following is NOT influenced by gravity?

A.   Earth's tides
C.   Earth's orbit
D.   magnetism

2. Gravity is a force that every mass exerts on every other mass. When you jump up in the air,
not only does the Earth exert a gravitational force on you, but you also exert a gravitational
force on the Earth. You, of course, fall back down to the Earth. Which of the following explains
why the Earth is not moving toward you when you jump up in the air?

A.   Earth exerts a gravitational force on itself.
B.   You don't weigh enough to affect Earth's surface.
C.   Your mass is very small compared to Earth's mass.
D.   Earth's fixed orbit around the Sun keeps it from moving

3. Ignoring mass and weight contributed by fuel, what happens when the space shuttle takes
off and moves away from Earth?

A.   Its mass decreases and weight increases.
B.   Its mass increases and weight decreases.
C.   Its mass remains constant and weight decreases.
D.   Its mass remains constant and weight increases.

4. Jermaine is being weighed at the doctor's office. Jermaine's weight depends on which of
the following?

A.   his height
B.   his mass
C.   his density
D.   his volume

5. The force of gravity on a person or object on the surface of a planet is called

A. mass
B. terminal velocity
C. weight
D. free fall
6. The law of universal gravitation states that any two objects in the universe that have mass,
without exception,

A. attract each other
B. repel each other
C. combine to provide a balanced force
D. create friction

7. The amount of matter in an object is called its

A. inertia
B. mass
C. force
D. balance

8. The force that pulls falling objects towards Earth is called

A. gravity
B. free fall
C. acceleration
D. air resistance

9. Look at the picture. At which point (A, B, C, or D) is the net force due to the gravitational
pull of both the Earth and the Moon closest to zero?

A.   Point A
B.   Point B
C.   Point C
D.   Point D

10. Sharon pushes a toy car and lets it go. The toy car rolls and gradually comes to a stop.
What would make the car stop?

A.   A force must be applied to the car in a direction opposite to that in which it is moving.
B.   A force must be applied pushing the car forward in the same direction as the moving car.
C.   A force must be applied in a direction pushing the car upward to make the car stop.
D.   A force must be applied in a direction pulling the car downward causing the car to stop.

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