Forces
Simple Machines
Levers
Motion
Lucky Dip
100
A force can be either a ______, _______ or _______.
Push, Pull or Twist
100
What is a simple machine?
A device that makes work easier and which has few or no moving parts.
100
The point where a lever rotates or pivots is called the _________
The fulcrum (turning point)
100
Describe an unbalanced force.
Unbalanced forces occur when separate forces are not equal in strength or they are not opposite in direction.
100
What is the metric unit used to measure force?
Newtons (N)
200
Forces can cause an object to change ________, _______, __________ or __________.
Shape, Direction, Speed up or Slow down
200
The six different simple machines are ____________
Lever, inclined plane, wedge, pulley, wheel and axle, and screw.
200
What are the three key components of a lever?
Fulcrum (turning point), Effort (input force), Load (output force)
200
The sum of all the forces acting on an object are called ____________.
Net forces
200
What is the measure of the amount of gravity on an object?
Weight
300
Identify the different forces that would be present in the image below by drawing a freebody diagram -
Thrust = Push, Normal = Perpendicular force
300
Identify at least one simple machine that makes up a fishing rod?
Example response -
Includes 3rd class lever, wheel & axle and pulley
300
Provide an example of a first class lever, a second class lever, and a third class lever.
First class: see saw or scissors. Second class: nut cracker or pushing a wheelbarrow. Third class: Tweezers or stapler.
300
SELECT THE CORRECT RESPONSE AND JUSTIFY
The greater the mass of an object:
a) the easier the object starts moving
b) the greater the inertia (state of rest)
c) the more balanced it is
d) the more space it takes up
The greater the mass of an object the greater the inertia. All objects resist changes in their state of motion. The more mass an object has a greater tendency to resist changes in its state of motion. This relates to Newton's First Law.
300
Newton's first law states _____________________________
An object at rest will stay at rest, and an object in motion will stay in motion at constant speed, unless acted upon by an unbalanced force.
400
Explain balanced forces, and provide an example.
When two forces acting on an object are equal in size but act in opposite directions, we say that they are balanced forces. A game of tug-of-war can be a perfect example of balanced forces. If the people on each side of the rope are pulling with the same strength, but in the opposite direction, the forces are balanced. The result is no motion.
400
Explain how a simple machine works as a force multiplier.
Force multipliers are devices that reduce the amount of force necessary to move an object. Force multipliers are useful for lifting heavy objects or doing other things that require large amounts of force. Levers, ramps and pulleys are simple machines that act as force multipliers.
400
If the load is closer to the fulcrum, is more or less effort required? Explain your response.
If the fulcrum is closer to the load, then less effort is needed to move the load a shorter distance. If the fulcrum is closer to the effort, then more effort is needed to move the load a greater distance. This creates mechanical advantage and is why levers can be very useful for lifting large loads with little effort.
400
If a force is going to the right at 300N, an opposite force going to the left at 500N, identify the net force and direction of movement.
Movement 200N to the left.
400
Identify the difference between a contact and a non- contact force. Provide an example of each.
A non-contact force is a force which acts on an object without coming physically in contact with it, whereas a contact force is a force applied to a body by another body that is in contact with it.
Contact Forces: Push, Pull, Friction, etc.
Non-contact Forces: Gravitational force, Magnetic force, etc.
500
Identify and explain at least 3 points of friction on a bicycle.
Example points -
Sample response: 1) Brakes against the tyres create friction to slow the bike, 2) Hand grips allow the rider to hold on and steer, 3) Friction between wheels and the road allow for forward movement.
500
I need to move a piano into a truck, what simple machine could I use? Why?
I could use an inclined plane (or ramp) to move the piano into the truck. The weight of the piano would be too difficult and heavy to move without a simple machine, and the incline plane will allow it to be pushed up into the back on truck.
500
On one side of a see saw, there is a person with a weight of 600N. He is sitting 3m away from the pivot. On the other side, is a person weighing 450N. How far away must they sit?
600 x 3 = 1800, 1800/450 = 4 metres
500
Calculate the Mechanical Advantage of the can crusher below -
Mechanical Advantage (MA) = distance to effort / distance to load
MA = 60cm / 20cm = 3
500
If an object has a greater density than water (1g/cm3), will it sink or float? Why?
The object would sink because for an object to float it needs to be less dense (lighter) than the liquid, in this case water it is in.