Forces 101
What is a force?
A push or pull
In Diagram A, which arrow shows the strongest force?
Arrow C
Lubricant, rollers and streamlining are all examples of how to reduce what force?
Friction
Which object has more gravity? The Sun or the Moon?
The Sun!
A feather falls off a magpie while it's flying by. What force slows the feather in its fall?
Air resistance
Fill in the blank: Mr Baird pushes a box with 40 ____ (units) of force.
N (Newtons)
In Diagram B, which examples show balanced forces?
Example A and C
What force prevents a stretched rope from breaking?
Tension
When two north magnets are brought close, they ____________ each other.
Repel
DOUBLE TROUBLE!!
Define weight and mass.
Weight: the amount of gravitational force acting on a object.
Mass: the amount of matter that makes up an object.
What is net force?
The total amount of force acting on an object.
What is the net force in Diagram D?
5N left
Friction acts in the __________ direction of motion.
Opposite
What is the force that builds up when two objects are rubbed together, passing electrons?
Electrostatic force
A man is using a trolley for his groceries. What force best describes the man's actions?
A push
A force that can act on an object from a distance, or touching it is known as a ___________ force.
Non-contact
DOUBLE TROUBLE!!
In Diagram C, which car is accelerating and why?
Describe the motion of the second car.
Car B, because the right arrow is longer than the left arrow (unbalanced horizontal forces).
Car A is travelling at a constant speed.
What force makes a car move forward?
Applied force
Jupiter has a gravitational force of 22N. How much does an alien with a mass of 100kg weight on Jupiter?
2200 N
A helicopter is flying over mountains. What force is slowing down the helicopter (horizontally?)
Drag
A an object with balanced forces has _________ net force.
Zero
In Diagram F, two kids are pulling their sister on a sled. What is the net force acting on the sled?
140 N right
(100 + 100 - 60)
Which of the following is NOT a contact force?
Air resistance, drag, magnetism, or tension?
Magnetism
A rock is dropped off a cliff and falls toward the earth due to gravity. What happens to the earth?
It moves slightly towards the rock due to the rocks gravitational force.
Reduce