Download Objectives: • Explain work in mechanical systems • Solve math

NAME ______________________________ Period ______
WORKSHEET PP. 84-93
WORK IN MECHANICAL SYSTEMS
ACTIVITY
DESCRIPTION
1. In mechanical systems, work is done when what? (1)
SCORE/POINTS
2. Write the equation for work and tell what each letter stands for (4)
1. NT
NOTES & STUDY QUESTIONS
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2. WS
PREVIOUS UNITS REVIEW
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3. In the English system, work is measured in (1)
4. In the SI system, work is measured in what 2 units?(2)
3. TX
PP 84-89 WORKSHEET
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4. MS
PRACTICE MATH
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Objectives:
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Explain work in mechanical systems
Solve math problems using the formula
Work = (Force)(Distance) W = FD
Solve for Work In, Work Out, and % Efficiency for simple
machines such and the Inclined Plane and various pulley
systems
Give the correct units for Work in both the English and SI
systems
Correctly interpret graphs and charts
Correctly list the Independent, Dependent and Control
Variables.
5. The distance and direction through which an object moves are
also called its what? (1)
6. Explain the difference between positive work and negative work.
(2)
7. Look at Example 2.1 then solve the following
(show: formula, work, answer, label= 4pts)
Find the amount of work done by a weight lifter in lifting a 220
pound barbell a distance of 4 feet.
8. Why is no “mechanical” work done on the barbell while the weight
lifter hold it in place above his head? (1)
9. What “biological work” is being done while holding a barbell? (1)
10. Look at example 2.2. Why is the answer negative? (1)
11. When you throw a ball the work done is force x distance. What
distance do you use, the distance your arm went, or the distance the
ball lands away from you? (1)
12. When the weight lifter does work on a barbell, the gravitational
potential energy gained by the barbell equals what? (1)
21. Look at example 2.3 and then solve the following.
A block and tackle is used to lift and engine.
The engine weighs 700 lbs and is moved 1.5 feet.
The operator pulls with a force of 120 lbs over a distance of 10 feet.
*1pt formula *1pt numbers in formula *1pt answer *1pt label
Find Work Input. (4)
13. When brakes slow down a cart, the cart loses kinetic energy. The
amount of kinetic energy lost equals what? (1)
14. Machines are designed to do what? (2)
Find Work Output (4)
15. Output work is always ___________than input work. (1)
16. Give an example of something that causes undesired but
unavoidable losses of energy. (1)
17. Efficiency is a ratio of (1)
18. Output work is work done by what? (1)
19. Input work is work done on what? (1)
20. Write the formula to calculate percent efficiency (1)
Find Efficiency in percent.(4)
Work = (Force)(Distance)
%Efficiency = Work Out x 100
Work In
PRACTICE MATH WORKSHEET
1. A horizontal force of 50 Newtons is applied to push a desk 25 meters across a
warehouse floor. FIND THE WORK DONE
a. Write the formula to find work (1pt)
_______________________
5. A person uses an inclined plane to move a box 3 feet up off the ground into the
back of a pickup truck. The box weighs 220 pounds. The inclined plane is 9 feet long
and the person pushes the box up that inclined plane with a force of 100 pounds.
Solve the following:
WORK OUT – THE BOX FROM THE GROUND TO THE TRUCK.
a. Write the formula to find work (1pt) _____________________________
b. Put the numbers and labels in the formula (1pt) _____________________
b. Put the numbers and labels in the formula (1pt)_______________________
c. Write the correct answer and label (2 pts) _______________________
c. Write the correct answer and label (2 pts) _________________________
2. A test shows that 200 ftlb of work is required to lift an object a distance of 5 feet.
FIND THE WEIGHT (FORCE) OF THE OBJECT
a. Write the formula to find force (weight)(1pt) _________________________
b. Put the numbers and labels in the formula (1pt) ______________________
c. Write the correct answer and label (2 pts) _______________________
3. A pulley system lifts a 400 lb weight a distance of 2 feet. The operator pulls the
rope with a force of 80 lbs. a distance of 12 feet. Solve for the following:
WORK OUT – WHAT THE PULLEY DOES
a. Write the formula to find work (1pt) _________________________________
b. Put the numbers and labels in the formula (1pt) _______________________
c. Write the correct answer and label (2 pts) _________________________
WORK IN – WHAT THE OPERATOR DOES
a. Write the formula to find work (1pt) ________________________________
WORK IN – WHAT THE PERSON DOES
a. Write the formula to find work (1pt) _____________________________
b. Put the numbers and labels in the formula (1pt) _____________________
c. Write the correct answer and label (2 pts) _______________________
% EFFICIENCY
a. Write the formula to find efficiency (1pt) _____________________________
b. Put the numbers and labels in the formula (1pt) _____________________
c. Write the correct answer and label (2 pts) _______________________
6. A person uses a lever to raise a 400 Newton box up a distance of 0.5 meters. The
person has to push down on the lever with a force of 200 Newtons a distance of 1.5
meters. Solve the following.
WORK OUT – WHAT HAPPENS TO THE BOX
a. Write the formula to find work (1pt) _____________________________
b. Put the numbers and labels in the formula (1pt) ______________________
b. Put the numbers and labels in the formula (1pt) _____________________
c. Write the correct answer and label (2 pts) ________________________
c. Write the correct answer and label (2 pts) _______________________
% EFFICIENCY
a. Write the formula to find efficiency (1pt) __________________________
WORK IN – WHAT THE PERSON DOES
a. Write the formula to find work (1pt) _____________________________
b. Put the numbers and labels in the formula (1pt) _____________________
b. Put the numbers and labels in the formula (1pt) _____________________
c. Write the correct answer and label (2 pts) _______________________
c. Write the correct answer and label (2 pts) _______________________
4. If you find that you have 850 Nm of output work and 900 Nm of input work,
calculate the percent efficiency.
a. Write the formula to find efficiency (1pt) _________________________
% EFFICIENCY
a. Write the formula to find efficiency (1pt) _____________________________
b. Put the numbers and labels in the formula (1pt) _____________________
b. Put the numbers and labels in the formula (1pt) _____________________
c. Write the correct answer and label (2 pts) _______________________
c. Write the correct answer and label (2 pts) _______________________