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Free-body Diagram

Free- body Diagram

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Free- body Diagram. Homework. To a 10.0-kg table, three forces were applied on it. F1=5.00 N, South F2=6.00 N, East F3=4.00 N, West Using the component method, what is the net force applied on the table?. Homework. To a 10.0-kg table, three forces were applied on it. - PowerPoint PPT Presentation

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Page 1: Free- body Diagram

Free-body Diagram

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Homework

To a 10.0-kg table, three forces were applied on it.

F1 = 5.00 N, South

F2 = 6.00 N, East

F3 = 4.00 N, West

1. Using the component method, what is the net force applied on the table?

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Homework

To a 10.0-kg table, three forces were applied on it.

F1 = 5.00 N, South

F2 = 6.00 N, East

F3 = 4.00 N, West

2. If a fourth force was applied and made the net force zero, what is the magnitude and direction of this fourth force?

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Homework

Provide the FBD of the system (in red text) in the following scenarios and identify the agents of all forces cited.

1. a stone in midair after thrown upwards

2. a balloon-powered car moving at a constant speed

3. a balloon-powered car moving with a completely deflated balloon

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Homework

• A certain balloon-powered car has a mass of 50.0 grams. The gushing air from its balloon provides a thrust force of 0.30 Newton. If the car is accelerating at 2.00 m/s2 for the first 5.00 meters, do you think friction is acting on the car? Defend your answer by showing your solutions.

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Objectives

• Recall the Laws of Motion. • Construct the free-body diagram of the

forces acting on a body. • Determine the magnitude of forces acting

on a body.

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Laws of MotionIn memory of the past lesson…

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Can you remember?

What are the three laws of motion

proposed by Einstein?

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Can you remember?

What are the three laws of motion

proposed by Isaac Newton?

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What law has this provision?

For every action, there is an equal but

opposite reaction.

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What law has this provision?

Every body continues in its state of rest, or of motion in a straight line

at constant speed, unless it is compelled to change that state by a

net force exerted upon it.

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What law has this provision?

The acceleration produced by a net force on a body is directly

proportional to the magnitude of the net force, is in the same direction as the net force, and is inversely proportional to the mass of the

body.

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Free-body Diagram

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Balloon-powered Cars

ALIN ANG NAIBA?

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Balloon-powered Cars

As the air is expelled from the balloon, the car moves. What are the forces acting on it?

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Free-body Diagram

A free-body diagram is a physical model that represents all forces acting on a system.

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Some Types of Forces

• Weight - the gravitational pull of the earth

• Friction - the contact force that acts to oppose sliding motion between surfaces

• Normal - the contact force exerted by a surface on an object

• Thrust - a general term for the forces that move objects

Read p. 94 of Glencoe for the complete list.

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When constructing the FBD,

Always identify the SYSTEM.

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Balloon-powered Cars

As the air is expelled from the balloon, the car moves. What are the forces acting on it?

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Balloon-powered Cars

As the air is expelled from the balloon, the car moves. What are the forces acting on balloon-powered car?

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How would one know that a force should be in the FBD?

For every force there should be

an AGENT.

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How would one know that a force should be in the FBD?

If you cannot identify the agent that applies or causes

the force, then that force should not be part of the

FBD.

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Balloon-powered Cars

What are the agents applying these forces?

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Qualitative FBD

.

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Quantitative FBD

• Construct the FBD.

MassesBear = 120 gTable = 12 kg

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355 g

125 g

25.0 kg1. Determine the magnitude of the weight (in Newton) of the following:

a. starb. blue pillowc. table

W = 1.23 N

W = 3.48 N

W = 245 N

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355 g

125 g

25.0 kg2. Determine the normal force acting on the following:

a. starb. blue pillow c. table

Fn = 1.23 N

Fn = 4.70 N

Fn = 250. N

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Simple Drills

F applied = 20.0 N

f = 20.0 N

Describe the direction of the system if it is at rest.

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Simple Drills

F applied = 20.0 N

f = 20.0 N

Describe the velocity of the system if it is at rest.

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Simple Drills

F applied = 20.0 N

f = 20.0 N

Describe the velocity of the system if it is moving 30 m/s.

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Simple Drills

F applied = 20.0 N

Describe the direction of the system if it is moving.

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Simple Drills

F applied = 20.0 N

Describe the velocity of the system if it is moving.

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Seatwork

• Use a piece of size 4. • Listen to the instructions carefully.

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Number 1

f = 15.0 N

Describe the motion of this body moving to the right. (speeding up, slowing down, constant velocity)

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Number 2

f = 15.0 N

Describe the motion of this body moving to the right. (speeding up, slowing down, constant velocity)

F applied = 20.0 N

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Number 3

f = 15.0 N

What is the net force acting on the body (magnitude and direction)?

F applied = 20.0 N

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Number 4

f = 15.0 N

If the body has a mass of 5.00 kg, what is its acceleration (magnitude and direction)?

F applied = 20.0 N

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Number 5

f = 15.0 N

How many seconds will it take for this body to increase its speed by 5.00 m/s?

F applied = 15.0 N

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End of Session