Understanding Effect Of Forces
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Understanding Effect Of Forces as PDF for free.
More details
- Words: 1,280
- Pages: 27
VIDEO……
(Playing See-saw)
From the video what can you observe?
BALANCED FORCES
UNBALANCED FORCES
Learning Outcomes
A student should be able to : • Describe the effects of balanced force acting on an object • Describe the effects of unbalanced force acting on an object
Balanced Forces Consider a physics book at rest on a table top 2 forces acting upon the book 2 forces are equal magnitude & in opposite directions, they balance each other.
When the forces acting on an object are balanced they cancel each other out. The net force acting on an object is equal to zero. (Acceleration = 0 m/s²)
When the forces acting upon the book balance each other, the book will be at equilibrium.
Unbalanced Forces Consider a physics book sliding from left to right across a table top 2 forces acting upon the book and balance each other no force present to balance the force of friction. the book moves to the right, friction acts to the left to slow the book down
When the forces acting on an object unbalanced, they not cancel each other, the net force is acting on an object. (Acceleration ≠ 0 m/s²)
there is unbalanced force , the book changes its state of motion. the unbalanced forces is directed opposite the book’s motion & will cause it to slow down the book is not at equilibrium.
A bird perching on a branch of a tree R (Reaction of the branch)
The forces of gravity, W pulls it downward and the reaction of the branch, R pushed the bird upward to balance the weight. The net or total force acting on the bird is zero and the bird is at rest.
W (Weight of the bird)
VIDEO…… (Golf Buggy)
From the video what do you think about a force? A velocity?
A golf buggy moving in a golf course R (Reaction of the ground)
F (Frictional Force)
T (Engine Force)
W (Weight of the golf buggy) T – drives the buggy forward T has the same magnitude with F (included air resistance), but acts in the opposite direction. The net horizontal force acting on the buggy is 0 W is balanced by the R on the buggy The net vertical force on the golf buggy is 0 So the buggy moves with a constant velocity
Toy car starts to move
Push the stationary toy car with the hand The toy car start to move The forces can moves a stationary object.
Toy car stop the moving
A toy car collides with a wall
The toy car is stop by the wall The forces can stops the motion of an object.
A cyclist use a bigger force to pedal his bicycle and increased its speed F The forces to the pedal is greater than the frictional forces acting on the bicycle. The resultant force, F causes the bicycle to accelerate forward.
Lorry moves from smooth surface to a rough surface smooth surface
rough surface
Move to
When a lorry moves from a smooth surface to a rough surface, the forces of friction retards the motion of the lorry and slow down a lorry moving (decelerate)
A tennis ball hit by the racket
When a tennis ball is hit by a racket, the reactive force causes the tennis ball to change its direction
Bending a straight ruler Straight ruler
A straight ruler forms an arc when bending forces are applied to Change to
both ends. The forces can change the shape of an object.
Bend ruler
start or stop moving object
change the size or shape of an object
change the direction of a moving object
change the velocity of a moving object
The effects of forces
move a stationary object
slow down a moving object
GROUP DISCUSSION
What can you observe from this pictures & situation given relate with the forces? Arm wrestling competition
Push the brakes down car
Tug of war
Arm Wrestling Competition Situation 1 Imagine if you compete against some one who is just about as strong as you.
Situation 2 Imagine if you compete against a world famous body builder.
When both of you are pushing
When both of you are pushing
The force exerted by each person is equal, but they are pushing in opposite direction.
His force will be much greater than yours.
as hard as you can your arm stay in the same place.
The 2 forces cancel each other & the resulting forces is 0. The is the situation of balance forces .
as hard as you can your arms will move in the direction he is pushing.
The forces that is equal to his force minus your force. The is the situation of unbalance forces.
Push the brakes down car
Situation Imagine that your family’s car breaks down on the road. You & your brother have to push it into the parking lot.
If you & your brother push the car, the resulting force on the car will be the sum of your forces. The direction of the forces of course in the direction that you are applying the forces.
The is the situation of unbalance forces.
Tug of War Situation 1 Imagine if you compete against team have a same strength. Similar to an arm wrestling
match, the force are moving away from each other.
If 2 teams have equal force, the rope will stay pretty much in same place. The 2 forces cancel each other & the resulting forces is 0. The is the situation of balance forces .
Situation 1 Imagine that you compete against US Olympic weight lifting team. Their force will probably be a little larger than yours. You will move in the direction they are pulling with a force that is equal to their force minus your force.
The is the situation of unbalance forces .
Conclusion from the situation FORCE Balance
Unbalance
Do not cause a change of motion.
Cause a change of motion.
The force are equal in size & opposite in direction.
The force are not equal in size & opposite in direction.
Two important thing to remember when working with balanced & unbalanced forces : •Forces in the same direction combine by addition •Forces in opposite direction combine by subtraction
TEST STUDENT UNDERSTANDING….
When the forces acting on an object are balanced, the object is remain at rest.
Sorry Sir, I think the object is either at rest or moving at a constant velocity…
Blur??????
Think about it….. Do you agree or not?
‘No net force’ does not mean that there are no forces acting on an object.
It simply means that all the forces are balanced
Learning Outcomes
A student should be able to : • Describe the effects of balanced force acting on an object • Describe the effects of unbalanced force acting on an object
start or stop moving object
change the size or shape of an object
change the direction of a moving object
change the velocity of a moving object
The effects of forces
move a stationary object
slow down a moving object
ASSIGNMENT…… Reading a subtopic – relationship between force, mass and acceleration for the next lesson (text book page : 37) Experiment : 1) to investigate the relationship between acceleration and force when the mass is constant 2) to investigate the relationship between acceleration and mass when the force is constant
(Playing See-saw)
From the video what can you observe?
BALANCED FORCES
UNBALANCED FORCES
Learning Outcomes
A student should be able to : • Describe the effects of balanced force acting on an object • Describe the effects of unbalanced force acting on an object
Balanced Forces Consider a physics book at rest on a table top 2 forces acting upon the book 2 forces are equal magnitude & in opposite directions, they balance each other.
When the forces acting on an object are balanced they cancel each other out. The net force acting on an object is equal to zero. (Acceleration = 0 m/s²)
When the forces acting upon the book balance each other, the book will be at equilibrium.
Unbalanced Forces Consider a physics book sliding from left to right across a table top 2 forces acting upon the book and balance each other no force present to balance the force of friction. the book moves to the right, friction acts to the left to slow the book down
When the forces acting on an object unbalanced, they not cancel each other, the net force is acting on an object. (Acceleration ≠ 0 m/s²)
there is unbalanced force , the book changes its state of motion. the unbalanced forces is directed opposite the book’s motion & will cause it to slow down the book is not at equilibrium.
A bird perching on a branch of a tree R (Reaction of the branch)
The forces of gravity, W pulls it downward and the reaction of the branch, R pushed the bird upward to balance the weight. The net or total force acting on the bird is zero and the bird is at rest.
W (Weight of the bird)
VIDEO…… (Golf Buggy)
From the video what do you think about a force? A velocity?
A golf buggy moving in a golf course R (Reaction of the ground)
F (Frictional Force)
T (Engine Force)
W (Weight of the golf buggy) T – drives the buggy forward T has the same magnitude with F (included air resistance), but acts in the opposite direction. The net horizontal force acting on the buggy is 0 W is balanced by the R on the buggy The net vertical force on the golf buggy is 0 So the buggy moves with a constant velocity
Toy car starts to move
Push the stationary toy car with the hand The toy car start to move The forces can moves a stationary object.
Toy car stop the moving
A toy car collides with a wall
The toy car is stop by the wall The forces can stops the motion of an object.
A cyclist use a bigger force to pedal his bicycle and increased its speed F The forces to the pedal is greater than the frictional forces acting on the bicycle. The resultant force, F causes the bicycle to accelerate forward.
Lorry moves from smooth surface to a rough surface smooth surface
rough surface
Move to
When a lorry moves from a smooth surface to a rough surface, the forces of friction retards the motion of the lorry and slow down a lorry moving (decelerate)
A tennis ball hit by the racket
When a tennis ball is hit by a racket, the reactive force causes the tennis ball to change its direction
Bending a straight ruler Straight ruler
A straight ruler forms an arc when bending forces are applied to Change to
both ends. The forces can change the shape of an object.
Bend ruler
start or stop moving object
change the size or shape of an object
change the direction of a moving object
change the velocity of a moving object
The effects of forces
move a stationary object
slow down a moving object
GROUP DISCUSSION
What can you observe from this pictures & situation given relate with the forces? Arm wrestling competition
Push the brakes down car
Tug of war
Arm Wrestling Competition Situation 1 Imagine if you compete against some one who is just about as strong as you.
Situation 2 Imagine if you compete against a world famous body builder.
When both of you are pushing
When both of you are pushing
The force exerted by each person is equal, but they are pushing in opposite direction.
His force will be much greater than yours.
as hard as you can your arm stay in the same place.
The 2 forces cancel each other & the resulting forces is 0. The is the situation of balance forces .
as hard as you can your arms will move in the direction he is pushing.
The forces that is equal to his force minus your force. The is the situation of unbalance forces.
Push the brakes down car
Situation Imagine that your family’s car breaks down on the road. You & your brother have to push it into the parking lot.
If you & your brother push the car, the resulting force on the car will be the sum of your forces. The direction of the forces of course in the direction that you are applying the forces.
The is the situation of unbalance forces.
Tug of War Situation 1 Imagine if you compete against team have a same strength. Similar to an arm wrestling
match, the force are moving away from each other.
If 2 teams have equal force, the rope will stay pretty much in same place. The 2 forces cancel each other & the resulting forces is 0. The is the situation of balance forces .
Situation 1 Imagine that you compete against US Olympic weight lifting team. Their force will probably be a little larger than yours. You will move in the direction they are pulling with a force that is equal to their force minus your force.
The is the situation of unbalance forces .
Conclusion from the situation FORCE Balance
Unbalance
Do not cause a change of motion.
Cause a change of motion.
The force are equal in size & opposite in direction.
The force are not equal in size & opposite in direction.
Two important thing to remember when working with balanced & unbalanced forces : •Forces in the same direction combine by addition •Forces in opposite direction combine by subtraction
TEST STUDENT UNDERSTANDING….
When the forces acting on an object are balanced, the object is remain at rest.
Sorry Sir, I think the object is either at rest or moving at a constant velocity…
Blur??????
Think about it….. Do you agree or not?
‘No net force’ does not mean that there are no forces acting on an object.
It simply means that all the forces are balanced
Learning Outcomes
A student should be able to : • Describe the effects of balanced force acting on an object • Describe the effects of unbalanced force acting on an object
start or stop moving object
change the size or shape of an object
change the direction of a moving object
change the velocity of a moving object
The effects of forces
move a stationary object
slow down a moving object
ASSIGNMENT…… Reading a subtopic – relationship between force, mass and acceleration for the next lesson (text book page : 37) Experiment : 1) to investigate the relationship between acceleration and force when the mass is constant 2) to investigate the relationship between acceleration and mass when the force is constant
Related Documents
Understanding Effect Of Forces
May 2020 24
Understanding Effect Of Forces
May 2020 13
Understanding Advertising Effect
May 2020 25
Forces
June 2020 17
Forces
May 2020 21
Six Forces Of Forex
May 2020 9More Documents from ""
Impulsive Force
May 2020 22
Understanding Effect Of Forces
May 2020 24
Electromagnetic Wave
May 2020 21
Pressure In Liquid
May 2020 20
Problem Based Learning (pbl)
May 2020 21