Slide 1 :
Slide 2 : Index
Slide 3 : Understand the ideas of motion and force
Describe Newton's three laws of motion
Understand the idea of inertia
Test Newton's three laws of motion in their class room
Slide 4 : Push can change the state of the object from one place to another.
Slide 5 : Pull can change the state of the object from one place to other. Force (contd..)
Slide 6 : Stretch and squeeze can change the state of the state of the object from one place to other. Force (contd..)
Slide 7 : Force (contd..) Twist can change the state of the object from one place to other.
Slide 8 : WHEN THERE IS A PULL ... WHEN THERE IS A PUSH... WHEN THERE IS A STRETCH... WHEN THERE IS A SQUEEZE ... WHEN THERE IS A TWIST... We experiences some effect called forces.
We can’t see forces but we can see the effect of a force. Force (contd..)
Slide 9 : The ball remains in its state of rest till an external force is acting on it.
Slide 10 : When an external force (push) is acting on a ball (object) at rest it changes its state (moves over the steps ). Newton’s first law (contd..) Push the ball
Slide 11 : object in motion tends to stay in motion Newton’s first law (contd..)
Slide 12 : When external force (Push of the rabbit) acting on the object (ball) which is in motion the object changes its position. Newton’s first law (contd..) Push the ball
Slide 13 : From the above observation... Newton’s first law (contd..) An object remains in its state of rest
if no external force is acting on it. An object remains in its state of motion
if no external force is acting on it. An object changes its state of rest or uniform motion if some external force acting on it.
Slide 14 : An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless an external force is acting on it. The above three statement can be written as a single statement which is the Newton’s first law In other words Every body continuous in its state of rest or in uniform motion Unless an external force is acting on it. Newton’s first law (contd..)
Slide 15 : When the car hits the wall……
The moving car stopped when a force (from the wall) is acting on it.
Driver who is moving along with the car could not able to stop himself when the car stopped.
Driver has inability to change his position by himself at that instant.
Slide 16 : When the truck hits the car……
The moving truck stopped when a force (from the car) is acting on it.
Ladder which is moving along with the truck could not able to stop itself when the truck stopped.
Ladder has inability to change its position by itself at that instant
Slide 17 : It is the natural tendency of objects to resist changes in their state of motion.
This tendency to resist changes in their state of motion is described as inertia. This can be said in a single statement Inability of an object to change its position by itself is called Inertia.
Slide 18 : Try the following activity to demonstrate inertia Why will the coin drop into the glass when a force accelerates the card? Why does the downward motion and sudden stop of the hammer tighten the hammer head?
Slide 19 : Smaller force is needed to move smaller mass Larger force is needed to move larger mass
Slide 20 : 10 n 30 n Smaller force give smaller acceleration Larger force give Larger acceleration Newton’s second law (contd..)
Slide 21 : If a bowling ball and a soccer ball were both dropped at the same time from the roof of a tall building, which would hit the ground with a greater force?
Acceleration due to gravity accelerates downwards all objects at the same rate.
Therefore the difference in forces would be caused by the different masses of the balls.
The mass of the bowling ball is greater than the mass of the soccer ball.
The bowling ball experience greater force than soccer ball.
So, bowling ball hit the ground first. Newton’s second law (contd..)
Slide 22 : Smaller force (F) is needed to move smaller mass (m)
Larger force (F) is needed to move larger mass (m)
So, Force is directly proportional to mass
F α m Smaller force (F) give smaller acceleration (a).
Larger force (F) give smaller acceleration (a).
So, Force is directly proportional to acceleration (a).
F α a Acceleration is produced when a force acts on a mass.
The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object). Newton’s second law states that the net force on an object is proportional to the mass and the acceleration that the object undergoes.
F = ma Newton’s second law (contd..)
: Look at the flying motion of birds.
A bird flies by the use of its wings.
The wings of a bird push air downwards.
The air reacts by pushing the bird upwards.
The direction of the force on the air (downwards) is opposite to the direction of the force on the bird (upwards).
These two forces are equal and opposite.
Slide 24 : Look at the flying motion of rocket.
Hot gases are pushed out from the bottom of the rocket as the rocket is thrust upward.
The force of the gases pushing against the surface of the earth is equal and opposite to the force with which the rocket moves upward.
These two forces are equal and opposite. Newton’s third law (contd..)
Slide 25 : Look at the recoil effect of the gun.
When we trigger the gun, the gun pushes the bullet forwards and the bullet pushes the gun backwards.
The bullet has a greater acceleration due to the fact that it has a smaller mass. (Newton's second law)
These two forces are equal and opposite. Newton’s third law (contd..)
Slide 26 : Try it
1. Blow up a balloon.
2. Hold the opening downward and release the balloon.
3. Repeat this several times, and observe what happens.
4. Now describe what happened using Newton's third law of motion. "For every action, there is an equal and opposite reaction." There fore the action and reaction forces can be represented in a single statement that we called as Newton’s second law. Newton’s third law (contd..)
Slide 27 : Click true or false Force is the effect of push or pull
A ball which is in motion can come to rest without any external force.
Working principle of rocket can be explained by using Newton’s second law.
Inability of an object to change its position by itself is called Inertia.
The below diagram can be explained by Newton’s third law. True False True False True False True False True False
Slide 28 : Very Good Back to the questions
Slide 29 : Try again Back to the questions