Unbalanced Forces

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Unbalanced Forces Motion
2
Balanced Forces

• Are forces that have a net force of zero
• Equal forces in opposite directions
• Balanced forces DO NOT change the motion of
  objects

3
Unbalanced Forces

• Has a net force that is not zero
• Unbalanced forces DO change the motion of objects

Object Moves to the Left
4
What are forces that have a net force of zero
called?

1. Balanced
2. Unbalanced
3. Equal
4. accelerating

5
What type of force allows you to stand up from a
chair?

1. Balanced
2. Unbalanced
3. Equal
4. Opposite

6
A ball has two forces acting on it. One force is
pushing it to the left, and a larger force is
pushing it to the right. In which direction will
the ball move?

• Right
• Left
• Up
• Down

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Energy and Machines
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Energy

• Is the capacity to do work
• Energy can be used to move muscles, operate
  machines, cook meals, and heat rooms.
• When you stand up, your body uses energy to hold
  itself up. Energy is needed to act against the
  force of gravity.

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Machines

• Machines also use energy to act against gravity
  and friction.
• A machine is something that replaces human
  effort.
• Whenever a machine moves against the pull of
  gravity it uses energy.

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Forms of Energy

• Heat energy, light energy, sound energy,
  electrical energy, chemical energy, and
  mechanical energy
• One form of energy can change into another form
  of energy.
• A light bulb changes electrical energy to light
  energy and heat energy.

11
Did you know?

• Some scientist have built machines that harness
  the energy from tides and waves. These machines
  turn the movement of water waves and tides into
  power that can be used to light nearby homes and
  businesses.

12
What is a device that replaces human effort?

1. A chemical
2. A machine
3. A heater
4. gravity

13
What is needed to operate a machine?

1. Force
2. Energy
3. Lift
4. Motion

14
Why does a machine that lifts
boxes off the ground need energy?

1. It needs energy to pull against the force of
   gravity.
2. It needs energy to pull against an electrical
   force.
3. It needs energy to pull against a chemical force.
4. It needs energy to pull against a heat source.

15
Which kind of energy is shown in this
illustration of a water wheel?

1. Chemical energy
2. Heat energy
3. Light energy
4. Mechanical energy