Podcast
Questions and Answers
What is defined as the rate at which work is done?
What is defined as the rate at which work is done?
- Mechanical Advantage
- Force
- Power (correct)
- Energy
In which type of lever is the fulcrum positioned between the load and the effort?
In which type of lever is the fulcrum positioned between the load and the effort?
- Inclined Plane
- Third-class lever
- First-class lever (correct)
- Second-class lever
How is the mechanical advantage of a machine defined?
How is the mechanical advantage of a machine defined?
- The difference between input and output forces
- The ratio of output force to input force (correct)
- The speed of the load divided by distance
- The total work input to output work ratio
Which of the following machines is specifically used to split objects apart?
Which of the following machines is specifically used to split objects apart?
What happens to the mechanical advantage in a second-class lever?
What happens to the mechanical advantage in a second-class lever?
What best describes an ideal machine?
What best describes an ideal machine?
What is the S.I. unit of work?
What is the S.I. unit of work?
Which machine allows the wheel to rotate around a fixed axle?
Which machine allows the wheel to rotate around a fixed axle?
Study Notes
Work
- Work is a force used to move an object over a distance in the direction of the force
- Measured in Joules (J)
Energy
- Energy is the ability to do work
- When we do work on an object, we change its energy
Power
- Power is the rate at which work is done
- Measured in Watts (W)
Machines
- A device that helps do work
- Can multiply the force that is applied
- Examples: lever, inclined plane, screw, pulley, wheel and axle
Input Force
- Force applied to the machine
Output Force
- Force the machine exerts to move an object
Mechanical Advantage
- Ratio of output force to input force
- Represents the effectiveness of a machine.
- In an ideal machine, Mechanical Advantage is equal to 1 - input force = output force
- In reality, the output force is always less than the input force due to friction.
Types of Machines
-
Lever: A rigid bar that rotates around a fixed point called a fulcrum.
- First-class Lever: Fulcrum is between the load and the effort.
- Second-class Lever: The load is between the fulcrum and the effort
- Mechanical advantage is always more than 1.
- Third-class Lever: Effort is between the load and the fulcrum
- Doesn't offer mechanical advantage but increases the speed of the load.
-
Inclined Plane: A sloping surface. The longer the inclined plane, the less force needed to move an object from a low to a high level.
-
Wedge: A movable inclined plane used to split things apart
-
Screw: A type of inclined plane that spirals around a cylinder. The closer the threads are on the screw, the more force is needed to turn it.
-
Pulley: A wheel with a groove for a rope to move along, used to change the direction of a force or to multiply the force.
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Wheel and Axle: A wheel attached to an axle, allowing the wheel to rotate around the axle, used for lifting and moving objects.
The Human Body as a Machine
- Our joints act as the fulcrum in levers. (e.g. bending our arms at the elbow).
- Our teeth act as wedges to break down food.
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Description
This quiz covers fundamental concepts in physics regarding work, energy, and power. It explores how machines function to facilitate work and the principles behind mechanical advantage. Test your knowledge on the types of machines and their applications.
