Machines
Let's Calculate
Work and Power
IV and DV
Just A Reminder
100
A _________________ is a device that helps do work by either overcoming a force or changing the direction of the applied force
What is a machine?
100
You apply 200 N to a machine and the machine applies 2,000 N to an object. What is the mechanical advantage? a.0 b.1,800 c.10 d.400,000
What is 10 (c) ?
100
Work is being done when a.you apply a force to an object. b.an object is moving after you apply a force to it. c.you exert a force that moves an object in the direction of the force. d.you do something that is difficult.
What is you exert a force that moves an object in the direction of the force? (c)
100
The variable that is changed by the scientist.
What is the independent variable?
100
A jar lid is an example of a a.lever. b.wheel and axle. c.screw. d.wedge.
What is a screw (c)?
200
_____________ _____________ is the work done on a machine; the work that YOU DO.
What is work input?
200
You apply (input) 25 N to a machine and the machine applies 50 N to an object. What is the mechanical efficiency? a. 200% b. 1,800% c. 10% d. 400,000%
What is 200%?
200
The unit for work is the a.joule. b.newton. c.meter. d.watt.
What is joule? (a)
200
The variable that we can observe and provides the scientist with data.
What is the dependent variable?
200
Which of the following is NOT a wedge? a.chisel b.bottle opener c.axe head d.knife
What is bottle opener (b)?
300
Which of the following is NOT an everyday machine? A. Chopsticks B. Scissors C. Wheelchair D. Wood
What is wood?
300
Which of the following could be a machine's mechanical efficiency? a.95 N•m b.95 J/s c.95 W d.95%
What is 95% (d)?
300
Which of the following is NOT an example of work according to the scientific definition of work? a.playing baseball b.pushing a wheelbarrow c.reading a chapter for homework d.bowling
What is reading a chapter for homework (c)?
300
Students are conducting an investigation on the effect of sunlight on the growth of trees. They put one tree in an area with a lot of sunlight and one tree in an area that does not get a lot of sunlight. They water both trees the same amount and they use the same type of fertilizer (plant food). What is the independent variable in this experiment? A. The amount of water the trees get B. The type of fertilizer the trees get C. The amount of sunlight the trees get D. The height of the trees.
What is the amount of sunlight the trees get (c)?
300
A ramp is an example of which simple machine? a.lever b.wheel and axle c.inclined plane d.pulley
What is inclined plane (c)?
400
True or False: Machines decrease the amount of energy that is needed to do work.
What is False?
400
You apply a 100 N to a machine and the machine applies 1,500 N to an object. What is the mechanical advantage? A. 15 B. 15,000 C. 150,000 D. 400,000
What is 15 (a)?
400
Juan and Anita each lift an identical stack of books the same distance onto a table, but Anita does the job twice as fast. Therefore, her actions involve twice as much a.work input. b.power. c.work output. d.efficiency.
What is power (b)?
400
Clara wants to know if people run faster in sandals or dress shoes. She decides she’ll do a scientific experiment to figure out which type of footwear is faster. What should the dependent variable be for Clara’s experiment? A. The person running in the race B. The type of shoe the person is wearing C. The distance of the race D. The amount of time it takes the person to run
What is the amount of time it takes the person to run (d)?
400
A zipper is made from three a.inclined planes. b.levers. c.wedges. d.screws.
What is wedges (c)?
500
14. The work output of a machine divided by the work input is the ____ of the machine. a.efficiency b.power c.effort d.resistance
What is efficiency?
500
You apply 10 N to a machine and the machine applies 10 N to move another object. Since the input force is equal to the output force, a.this machine is not useful. b.this machine moved the object a great distance. c.the mechanical advantage is 1. d.this machine changed the input force.
What is the mechanical advantage is 1 (c)?
500
You push a 75 N box 3 m across the floor. How much work has been done?
What is 225 J?
500
Students want to determine which type of plant will best survive in a hot, dry environment. They place four different types of plants in identical pots, and put all of the plants by the same large window. They give each plant the same amount of water every day. Which of these is the independent variable for the students' experiment? A. amount of water B. health of plant C. type of plant D. amount of sunlight
What is type of plant (c)?
500
Which simple machines are known to have been used by the Egyptians to move and stack the huge blocks that form the Great Pyramids? a.wheel and axle b.wedge and screw c.lever and inclined plane d.pulley and block and tackle
What is lever and inclined plane (c)?
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