# Newton’s third law of motion - PowerPoint PPT Presentation

1 / 13

Newton’s third law of motion. Action/Reaction Pairs. Review: Newton’s 1 st & 2 nd Laws. Give a real life example of Newton’s 1 st Law of Motion. What is another name for Newton’s 1 st Law. What formula is associated with Newton’s 2 nd Law of Motion?

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Newton’s third law of motion

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

## Newton’s third law of motion

Action/Reaction Pairs

### Review: Newton’s 1st & 2nd Laws

• Give a real life example of Newton’s 1st Law of Motion.

• What is another name for Newton’s 1st Law.

• What formula is associated with Newton’s 2nd Law of Motion?

• Give a real life example of Newton’s 2nd Law of Motion.

### Oh No – Flying Balloons!

• What caused the balloon to fly across the room?

• Does it have an engine?

• Is it being pulled by an invisible string?

### Newton’s 3rd Law of motion

• For every action force, there must be an equal and opposite reaction force.

• Forces occur in pairs.

• Action Forces

• Reaction Forces

### An example of Action/Reaction Pairs.

• When a person jumps on a trampoline, he or she exerts a downward force on the trampoline = action force.

• The trampoline then exerts an equal force upward, sending the person high into the air = reaction force.

### Newton’s 3rd Law in Nature

• What action/reaction forces cause a fish to propel through the water when they are swimming?

### Let’s Explain….

• Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards (action force). In turn, the water reacts by pushing the fish forwards (reaction force), propelling the fish through the water.

• The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards).

### How do birds fly?

• What action/reaction pair allows a bird to fly through the air?

• Why can’t we fly?

### Let’s Explain…

• Consider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push air downwards. In turn, the air reacts by pushing the bird upwards.

• The size of the force on the air equals the size of the force on the bird; the direction of the force on the air (downwards) is opposite the direction of the force on the bird (upwards).

• Action-reaction force pairs make it possible for birds to fly.

### One more example…Rockets!

• The reaction of a rocket is an application of the third law of motion. Various fuels are burned in the engine, producing hot gases.

• The hot gases push against the inside tube of the rocket and escape out the bottom of the tube. As the gases move downward, the rocket moves in the opposite direction.