FORCES Physical Science 1st Semester

ASSIGNMENT PAGE

NUMBERS DUE DATE

HW POINTS

EARNED

Forces Vocabulary 1 /5

Learning Targets: Forces 2-3 /5

Net Force Practice 4-5 /5

Newton’s Laws Graphic Organizer 6 /5

Force and Acceleration 7 /5

Mass, Weight and Momentum 8-9 /5

Newton’s 3rd Law 10 /5

Forces Review 11-13 /5

TOTALS /40

NAME: ____________________________

CLASS PERIOD: ________

TEACHER: ________________

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Term What do you think this means? Definition Picture

Force

Newton

Net Force

Friction

Air Resistance

Gravity

Terminal Velocity

Mass

Weight

Inertia

Momentum

Law of Conservation

of Momentum

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Physical Science Text Book Chapter 12 Answer the following questions to identify your level of understanding:

Learning Targets: 1- Below Standard 2- Approaching Standard 3- At Standard 4- Above Standard

A. I can draw and use a free body diagram (FBD).

Draw a FBD for an object not moving on a table.

Explain the two states of motion for an object with balanced forces acting on it.

Draw a FBD and explain the motion of an object with unbalanced forces acting on it.

Draw a FBD for a box sliding down a ramp.

Activities/Vocabulary:

B. I can explain & apply Newton’s 1st Law of Motion.

Restate Newton’s 1st Law in your own words.

What is inertia? Describe how inertia affects the state of motion of a passenger in a car in a head-on collision if they are not wearing their seat belt.

Explain why some baseball players use bats of different sizes.

Activities/Vocabulary:

C. I can explain & apply Newton’s 2nd Law of Motion.

What is the famous formula that summarizes Newton’s 2nd Law? What is the force required to get a 4 kg box accelerating at 13.2 m/s2?

A 60 N force is used to push a 5 kg box that is resisted by 25 N of friction. Draw a FBD and identify the net force acting on the box.

What is the acceleration of the box in the level 2 question to the left?

Does it take more force to hit a baseball off of a fastball or a changeup (slow pitch)? Explain.

Activities/Vocabulary:

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Learning Targets: 1- Below Standard 2- Approaching Standard 3- At Standard 4- Above Standard

D. I can explain & apply Newton’s 3rd Law of Motion.

Restate Newton’s 3rd Law in your own words.

If a bag of candy exerts a 5 N force on the floor, what force does the floor exert on the candy?

Explain three force pairs involved in the sail car experiment (think about the whole experiment).

Explain why things can move even though all forces come in pairs.

Activities/Vocabulary:

E. I can explain how gravity affects the motion of objects.

What is the acceleration due to gravity on Earth?

Explain the difference between mass and weight.

If an astronaut has a mass of 76 kg, what would he weigh on the moon where the acceleration due to gravity is 1.67 m/s2?

If you throw a rock straight down off a bridge toward the river below, what is the initial downward velocity if the rock hits the water with a velocity of 34 m/s after falling for 1.2 seconds?

Activities/Vocabulary:

E. I can describe and calculate momentum.

Which two factors affect the momentum of an object? Write the correct formula for momentum.

How much momentum does a 27.35 kg object have when it moves at a velocity of 19.2 m/s?

What is the velocity of a 96.4 kg object when it’s momentum is 1342.9 kg*m/s?

Who has more momentum, a 63kg Ms. Tamura running with a velocity of 23.7 m/s or a 117.1kg Coach Byrd running at 12.25 m/s?

Activities/Vocabulary:

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In each of the pictures below calculate the net force acting on the object (include direction):

10N

5N 6N

8N

4N 11N

7N

164N

164N

15N

20N

2N

7N 5N 3N 5N

12N 2N

Drawing Free-body diagrams:

1. Free-body diagrams for four situations are shown below. For each situation, determine the net force acting upon the object.

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2. Free-body diagrams for four situations are shown below. The net force is known for each situation. However, the magnitudes of a few of the individual forces are not known. Analyze each situation individually and determine the magnitude of the unknown forces.

3. An egg is free-falling from a nest in a tree. Neglect air resistance.

4. A rightward force is applied to a book in order to

move it across a desk with a rightward acceleration. Consider frictional forces. Neglect air resistance.

5. A skydiver is descending with a constant velocity. Consider air resistance.

6. A football is moving upwards towards its peak

after having been booted by the punter.

7. A car is coasting to the right and slowing down.

Conclusion Questions:

1. Suppose two 4 Newton forces act on an object in the same direction. What is the net force on the object?

2. Five different forces act on an object. Is it possible for the net force on the object to be zero? Explain.

3. What happens to an object when an unbalanced force acts on it?

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Newton’s Laws Graphic Organizer

Newton’s 1st Law- Newton’s 2nd Law Newton’s 3rd Law

Name

Definition

Example #1

Own Definition

Example #2

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A force is a push or a pull. To calculate force we use the following formula:

F = ma where F = force in Newtons

M = mass in kilograms

A = acceleration in m/sec2

Example: With what force will a rubber ball hit the ground

if it has a mass of .25 kg?

Answer: F = ma

F = (.25 kg) (9.8 m/sec2)

F = 2.45 N

1. With what force will a car hit a tree if the car has a mass of 3,000 kg and it is accelerating at a

rate of 2 m/sec2?

Answer: ___________________

2. A 10 kg bowling ball would require what force to accelerate it down an alleyway at a rate of 3

m/sec2?

Answer: ___________________

3. What is the mass of a falling rock if it hits the ground with a force of 147 Newtons? (Note:

remember the acceleration of gravity…9.8 m/sec2)

Answer: ___________________

4. What is the acceleration of a softball if it has a mass of .50 kg and hits the catcher’s glove

with a force of 25 Newtons?

Answer: ___________________

5. What is the mass of a truck if it is accelerating at a rate of 5 m/sec2 and hits a parked car with

a force of 14,000 Newtons?

Answer: ___________________

F

M • A

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Mass, Weight, and Momentum

Use the following formula to solve for weight: Weight (W) = Mass (m) x gravity (g)

W = mg Mass is measured in kilograms (kg) Gravity on earth is a constant: 9.8 m/s2

Weight is measured in Newton’s (1 N = 1 kg * m/s2)

Momentum (p) = Mass (m) x velocity (v) p = mv

Mass is measured in kilograms (kg) Velocity is measured in meters/second (m/s) Momentum is measured in kilograms*meters/second (kg*m/s)

Answer the following questions – USE THE 4-STEP METHOD

1. Describe what will happen (if anything) to mass and weight when you go to the moon. 2. Why would this happen? 3. Find the weight of a 60 kg astronaut on earth 4. Find the weight of the same object on a planet where the gravitational attraction has been reduced to 1/10 of the earth’s pull. Show all work. 5. A backpack weighs 8.2 Newtons and has a mass of 5 kg on the moon. What is the strength of gravity on the moon? (Be careful with units, remember 1N= 1 kg * m/s2) 6. A physical science text book has a mass of 2.2 kg a. What is the weight on the Earth? b. What is the weight on Mars (g = 3.7 m/s2 )? c. If the textbook weighs 19.6 Newtons on Venus, what is the strength of gravity on Venus?

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7. Of all the planets in our solar system, Jupiter has the greatest gravitational strength. a. If a 0.5 kg pair of running shoes would weigh 11.55 Newtons on Jupiter, what is the strength of gravity there? b. If he same pair of shoes weighs 0.3 Newtons on Pluto, what is the strength of gravity on Pluto?

c. What does the pair of shoes weigh on earth?

8. A locomotives mass is 18181.81 kg. What is its weight?

9. On the moon, acceleration due to gravity is 1.6 m/s2. What is the mass of an astronaut, on the moon, whose weight is

648 N?

10. An F-14’s mass is 29,545 kg. What is its weight?

11. What is the mass of an object traveling 8 m/s with a momentum of 50 kg*m/s?

12. What is the momentum of a semi-truck with a mass of 2000 kg traveling 33.45 m/s?

13. Which has more momentum: A 5.6 kg bowling ball traveling at 12.4 m/s or a bullet weighing 0.13 kg traveling at

215 m/s?

14. A toy car with a mass of 0.75 kg is rolled across the floor at a rate of 4 m/s. It then collides into another car with a

mass of 1.5kg and the two cars continue rolling. What is the final velocity of the two cars?

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Forces Review Multiple Choice: 1. If you were on the moon, there would be a change in your

a) mass b) weight c) volume d) mass and weight

2. Which law of motion explains motion when balanced forces are acting on an object? a) 1st b) 2nd c) 3rd d) none of the laws

3. The force of gravity on a large object is _____ the force of gravity on a small object. a) greater than b) smaller than c) the same as

4. The acceleration due to gravity is a) larger for a 5kg mass than a 2kg mass b)smaller for a 5kg mass than a 2kg mass c)the same for a 5kg mass and a 2kg mass

5. Acceleration depends on a) the unbalanced force b) mass c) unbalanced force and mass d) none of these

6. Force is measured in a) Newtons b) kg c) m/s/s d) Newtons and kg

7. 1 Newton is equal to a) 1 kg b) 1 m/s2

c) 1 kg • m/s d) 1 kg •m/s2

8. Weight is measured in a) Newtons b) kg c) m/s/s d) Newtons and kg

9. If a force pushing an object is causing the object to move at constant speed, the force is a) greater than friction b) less than friction c) equal to friction

Calculations: SHOW ALL WORK! 10. An astronaut has a mass of 50kg. A) How much does gravity pull on her while she is on the earth (meaning, what is her weight)?

B) When she is at the space station, 6400 km above the earth, gravity is one-fourth the strength that it is on earth. What is her weight at this point?

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11. An originally stationary car with a mass of 1500kg accelerates at 3m/s2. How much force was required to reach this

acceleration?

12. A 450 N force is acting on a 16kg object traveling at a constant speed. A) What is the object’s acceleration?

B) How much friction is acting on the object?

13. A 56kg wagon is pushed with a net force of 200 N. What is the acceleration of the wagon? 14. An object accelerates at a rate of 3 m/s2 with a net force of 24N, what is the object’s mass? 15. A 45 N force is used to push an 8 kg box that is resisted by 10 N of friction. A. Draw a picture of the scenario. B. What is the net force acting on the box?

C. What is the acceleration of the box?

Short Answer. Write complete sentences, using the appropriate law!

16. What would be true of an object that has unbalanced forces acting on it (discuss both velocity and acceleration)?

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17. A friend helps you pull a box across the (frictionless) ice. Draw a picture for each situation and answer the question.

A. You pull with a force of 10N. Your friend pulls with a force of 15N in the same direction. What is the net force on the box?

B. If your friend now pushes in the opposite direction as you, what is the net force? C. What is the net force if you both push with 5N of force on opposite sides of the box?

18. Momentum= mass x velocity. If a small car and a large truck are moving with the same velocity, which one has the

greater momentum? 19. A soccer player kicks a soccer ball. Explain the forces involved in reference to Newton’s 3rd law. Also explain why the soccer ball goes forward instead of the player going backwards (Newton’s 2nd law).

20. Suppose a cart is being moved by a certain unbalanced force.

A. If the net force is cut in half, by how much does the cart’s acceleration change? B. If the cart force triples, by how much does the acceleration change? C. If the force remains the same, but the cart’s mass quadruples, what happens to the acceleration?