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# Forces

Unit 4 Lesson 2
by

## Natalie Howell

on 5 February 2016

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#### Transcript of Forces

Forces
Force
Balanced vs. Unbalanced Forces
Net Force
Practice Questions
Examples
Forces Acting on All Objects
Friction
Any push or pull on an object. Measured in Newtons (N).
Balanced Forces
When equal forces act on an object in opposite directions (
no acceleration
)
The combination of all the forces
acting on an object
Balanced/Unbalanced
Forces
If two students pull a wagon in opposite directions but the wagon does not move, the forces acting on the wagon are.....
a) accelerating negatively
b) unbalanced
c) accelerating positively
d) balanced
Gravity
A force that opposes the motion of an object. Occurs when 2 or more objects come in contact.
Types of forces
Contact force - applied when 2 objects touch
Noncontact force - one that an object can apply without touching another object
Ex: magnetic force (gravity)
Ex: Friction
Unbalanced Forces
When forces acting on an object are NOT equal.
Results in changes in motion (
acceleration
), always in the direction of the greater force.
Net force does NOT equal zero
Net force equals zero
Combining forces in the same direction
the sum of the individual forces
direction is same as the forces
Combining forces in opposite directions
add up forces in each direction separately
whichever direction has greater total force, object will move in that direction
Net Force
Which changes when unbalanced forces act on an object?
a) color
b) mass
c) motion
d) weight
A car is turning while moving at a constant speed. Are the forces acting on the car balanced or unbalanced? Explain
Three people push a piano on wheels with forces of 130 N to the right, 150 N to the left, and 165 N to the right. What is the strength and direction of the net force on the piano.
Which is an example of balanced forces?
a) A student increases his speed as he rides a bicycle.
b) One student pushes a cart forward while another pushes it in the opposite direction with the same force.
c) Two children help each other push a grocery cart around a corner.
d) A bat strikes a baseball.
An attractive force that exists between all objects that have mass
The strength of the force depends on two things
The distance between the objects
The mass of the objects
1) You push a book sitting on a desk with a force of 5 N, but the book does not move. What is the force of the friction?
a) 0 N
b) 5 N
c) between 0 N and 5 N
d) greater than 5 N
2) Which force slows a book sliding on a table?
a) gravity
b) sliding friction
c) rolling friction
d) fluid friction
3) How would the gravitational force between Earth and the Moon change if the distance between them increased?
This is called the Universal Law of Gravitation - this was created by Sir Isaac Newton
Subtract (greater force - smaller force)
Full transcript