Work
What is the Joule?
The unit for power
What is a watt?
The 6 simple machines
What is a pulley, lever, wheel & axle, wedge, screw, and inclined plane
The formula for work
What is force x distance
If a man is pushing a box 5 meters with a force of 10 Newtons, how much work is being done?
50 J
What is a Joule? (Another name for the unit)
A Newton-Meter
Is it possible to have a machine with 100% efficiency? Why or why not?
No, because of friction acting on output force.
The formula for power
What is work divided by time
You push on a skateboard with a force of 20N. The output force is 10N. What is the efficiency?
50%
What is work?
Using a force to move an object a certain distance
What is power?
How well a machine works
What is efficiency?
Formula for mechanical advantage
Say you're rock climbing with a friend and you're carrying a pack that weighs 70N. You climb to the top of a mountain, 40 meters up. How much work did you do on the pack?
2,800 J
What is the difference between input force and output force?
Input = what you put in
Output = what the machine puts out
If a tow truck does 10,000 J of work in 5 seconds, then the power of the truck is?
2,000 W
What are force, distance, and direction?
The formula for efficiency?
(Output work/Input work) x100
Two physics students, Ben and Bonnie, are in the weightlifting room. Bonnie lifts the 50 kg barbell over her head (approximately .60 m) 10 times in one minute; Ben lifts the 50 kg barbell the same distance over his head 10 times in 10 seconds. Which student does the most work?
A child pulls a sled up a snow-covered hill. The child does 405 J of work on the sled. If the child walks 15 m up the hill, how large of a force must the child exert?
27 N
What does it mean if an automobile company says their cars are more powerful than their competitor's cars?
They do more work in less time
Describe the mechanical advantage when you change each of the following:
Increase distance
Increase force
Change direction
Less than 1, greater than 1, equal to 1
How would you find the ideal mechanical advantage of the following simple machines: inclined plane, wedge, and wheel & axle?
Inclined Plane: length of ramp/height of ramp
Wedge: Length/Width
Wheel & Axle: Radius of Wheel/Radius of Axle
How much power will it take to move a 10 kg mass at an acceleration of 2 m/s/s a distance of 10 meters in 5 seconds? This problem requires you to use the formulas for force, work, and power all in the correct order.
40 watts (W)