Forces and Motion 1
What happens to an object when an unbalanced force acts on it?
can start moving, speed up or change direction
Student A is pushing a box with a force of 20N to the right. Student B is pushing with a force of 20 N to the right. Will the box move?
yes to the right!
Newton's Third Law
What is a second class lever and give an example
The load is in the middle
Eg. wheelbarrow, nut cracker
A change in position is called
Motion
Unit of measurement for force
Newtons
Forces that cause a change in motion are called..
unbalanced forces
Friction in the air is called...
Air Resistance
Two ways to increase friction
- Make the surface rougher
- Increase the pressure between surfaces
- increase the surface area
A large rock is motionless on a flat sidewalk. Which statement best explains why the rock remains motionless?
A) There are no forces acting on the rock.
B)The only force acting on the rock is directed toward the sidewalk.
C) The forces acting on the rock are all balanced
D) The sidewalk exerts an unbalanced force on the rock.
C
A force between two surfaces which prevents them from sliding past one another. A force that acts in the opposite direction of the traveling object
Friction
Student A is pushing a box with a force of 20N to the right. Student B is pushing with a force of 25 N to the left. What is the net force of this situation
5 N to the left
In a game of tug-o-war, what happens when the forces exerted by Team A and Team B are balanced?
neither team wins
What is Newton's Third Law of Motion?
For every action there is an equal and opposite reaction.
What does Archimedes Principle state?
That the buoyant force is equal to the weight of the fluid that the object displaces
Explain how
Unbalanced
Forces on an object that are equal in size and opposite in direction, cancelling each other out are called...
Balanced Forces
As motion increases friction ________.
decreases
Explain how density applies to buoyancy
the less dense an object, the more likely it is to float. If two objects of the same volume but different densities are placed in water, then the object that is more dense than water will sink
Name two different simple machines
wedge, pulley, wheel and axle, inclined plane, lever, screw
What is Newton's Second Law of Motion?
The greater the mass of an object, the more force it will take to accelerate.
F= m x a
What is Newton's First Law of Motion?
An object at rest will stay at rest and an object in motion will stay in motion, unless acted upon by an unbalanced force.
Danielle pulled gently on a spring scale. The scale showed a force, but the block did not move. Why not?
a. The force that she applied was balanced by another force.
b. The string between the spring scale and the block was not strong enough.
c. The spring scale was broken, so there was no force when she pulled on it.
d. There was not enough friction for the block to move.
a. The force that she applied was balanced by another force.
Which of the following objects will have the greatest change in motion?
a. a small force applied to an object with a large mass.
b. a small force applies to an object with a small mass.
c. a large force applied to an object with a large mass.
d. a large force applied to an object with a small mass.
d. a large force applied to an object with a small mass.