FOT Semester Exam
Wednesday, May 25 - Free Response
Thursday, May 26 - Multiple choice
You must have a calculator for free response – NO SHARING and NO CELL PHONES
Semester Exam is worth 1/6th of your FOT final grade
REVIEW
For each problem:1) List all given information2) Sketch a diagram if required3) Write the applicable formula and rearrange if necessary4) Substitute the known values and solve for unknown5) Show correct units6) Circle/ Box the correct answer.
1. You carry a basket of laundry weighing 25 pounds up a flight of stairs with a total height of 9 feet. How much work did you do (keep all units)?
REVIEW
W = ?F = 25 lbsD = 9 ft
List Given Information
Write FormulaW = F x D
Substitute Values
W = 25 lbs x 9 ft
Solve
W = 225 ft-lbs
Review
2010 Hummer H2• Output = 320 miles• Input = 32 gallons• Efficiency = ?
2010 Toyota Prius• Output = 500 miles• Input = 10 gallons• Efficiency = ?
Eff=Wo / WiEff= 500 mls / 10 gal
Eff = 50 mpg
Eff=Wo / WiEff= 320 miles / 32 gal
Eff = 10 mpg
3. A hot air balloon carries 300 lbs cargo, 250 lbs human, and 450 lbs materials up a distance of 2,000 feet. How much work did the balloon do (keep all units)?
Review
W = ?F = 300 lbs+ 250 lbs +450lbsD = 2,000 ft
List Given Information
Write Formula
W = F x D
Substitute Values
W = 1,000 lbs x 2,000 ft
Solve
W = 2,000,000 ft-lbs
Review
4. A physical therapy doctor told his 200-lb patient to do 30,000 ft-lbs of work each day to rehabilitate his leg. The patient decides to climb a hill to perform this work. How high does the patient need to climb in order to meet his goal?
W = 30,000 ft-lbsF = 200 lbsD = ??
List Given Information
Write Formula
W = F x D
Substitute Values
30,000 ft-lbs 200 lbs x DSolve
lbs
lbsftD
200
000,30
D = 150 ft
Review
5. A 1st class lever is used to lift a fallen log that weighs 120 lbs. The log is located 3 ft from the fulcrum. A child can apply a 12 lb force on the other side. How far from the fulcrum should the child stand?
120 lbs
3 ft. DF = ?
F = 12lbs
L = 120 lbsDL = 3 ftF = 12 lbsDF = ???
List Given Information
Write Equation
Sketch Diagram
LxDL=FxDFSubstitute and Solve
120lbs x 3 ft = 12 lbs x DFDF = 30 ft
Review
6. A gardener is capable of applying 50 lbs to lift a wheelbarrow. His hands are placed 4 ft from the axle. If the dirt is located 2 ft from the axle, how much dirt can the gardener carry?
2ft
DF = 4ft
F = 50lbs
L = ?DL = 2 ftF = 50 lbsDF = 4ft
List Given Information
Write Equation
Sketch Diagram
LxDL=FxDFSubstitute and Solve
L x 2 ft = 50 lbs x 4ftL = 100lbs
Review
6. A 3rd class mechanical lever is used to remove snow without damaging the pavement. The machine can apply 600 lbs of fore. The distance from the load to the fulcrum is 8 ft. The distance to the applied force is 4 ft. What is the maximum amount of snow removed, what is the mechanical advantage?
DF= 4ft
DL = 8ft
F = 600lbs
L = ?DL = 8 ftF = 600 lbsDF = 4ft
List Given Information
Write Equation
Sketch Diagram
LxDL=FxDFSubstitute and Solve
L x 8 ft = 600 lbs x 4ftL = 300lbs M.A. =1/2
Review
8. A fixed pulley system is used to lift a bucket from a well. How many pounds are required to lift 60 lbs of water.
MA = 1L = 60 lbsF = ??
List Given Information
Write Equation
Sketch Diagram
Substitute and Solve1 = 60 lbs / F
F
LMA
F = 60 lbs
Review
9. A movable pulley system is used to lift a bucket from a well. How many pounds are required to lift 60 lbs of water.
MA = 2L = 60 lbsF = ??
List Given Information
Write Equation
Sketch Diagram
Substitute and Solve2 = 60 lbs / F
L = 60lbsF
LMA
F = 30 lbs
Review
10.A block and tackle pulley system is used to lift a bucket from a well. How many pounds are required to lift 60 lbs of water.
MA = 3L = 60 lbsF = ??
List Given Information
Write Equation
Sketch Diagram
Substitute and Solve3 = 60 lbs / F
F
LMA
F = 20 lbs
11. A Lexus RX400h hydrid carries a 288-volt battery stystem. The batteries power electric motors that use 44.8 kW of power. What is the current traveling through this high voltage current. What is the resistance?
REVIEW
P = 44,800 WI = ?V = 288 V
List Given Information
Write FormulaP = I x V
V = 288V
I = ?
-
+P = 44,800 W
44,800 W = I x 288 VI = 156 A
11. A Lexus RX400h hydrid carries a 288-volt battery stystem. The batteries power electric motors that use 44.8 kW of power. What is the current traveling through this high voltage current. What is the resistance?
REVIEW
V = 288 VI = 156 AR = ??
List Given Information
Write FormulaV = I x R
V = 288V
I = ?
-
+P = 44,800 W
288 V = 156 A x RI = 1.85 Ohm
U3e-L3
12. Use the Schematic to solve for RA, RB, and RT
4 W
12W 10 W
40 W
21
111
RRRA
12
1
4
11
AR 3
1
12
41
AR3AR
10
1
40
11
BR 10
1
40
11
BR 8
1
40
51
BR8BR
U3e-L3
12. Use the Schematic to solve for RA, RB, and RT
4 W
12W 10 W
40 W
83 BAT RRR
11TR
U3e-L3
13. Use the Schematic to find the total resistance of the circuit
1.5W7 W
6 W
21
111
RRRP
7
1
6
11
PR 42
13
42
6
42
71
PR23.3PR
21 RRRT 73.423.35.1 TR
U3e-L3
14. Use the Schematic to solve for R
4 W
120V R=? 40 W
5 Amp
V = 120VI = 5 AR = ??V = IxR
List Given Information
120 V = 5A x RR = 24 Ohm
U3e-L3
14. Use the Schematic to solve for R
4 W
120V R=? 40 W
5 Amp
40
11
24
1
R 40
1
24
11
R 120
2
120
3
120
51
R
R = 60 Ohm
U3f – L3
15.A sample of hydrogen gas is compressed from 300 cm3 to 2 cm3. Its pressure is now 5 psi. What was the original pressure of the helium?
Step 1: Write given information
P1 = ?
V1 = 300 cm3
P2 = 5 psi
V2 = 2 cm3
Step 2: Write the formula and solve
P1V1 = P2V2
P1 x (300 cm3) = 5 psi x (2 cm3)
P1 x (300 cm3) = 10 psi*cm3
300 cm3 300 cm3
P1 = 0.0333 psi
U3f – L3
16. The surface of a concrete block that touches the ground is 1.5 ft^2. What is the pressure on the ground if the block weighs 25 lbs
Step 1: Write given information
P = ?
F = 25 lbs
A= 1.5 ft2
Step 2: Write the formula and solve
P=F/A
P = 25 lbs/1.5 ft^2
P = 16.7 psf
U3f – L3
17. What would hurt more: 25 lbs against 1 square inch of your body or 5 pounds against 0.01 square inches
Step 1: Write given information
P1 = ? P2 = ?
F1 = 25 lbs F2 = 5 lbs
A1= 1 in2 A2= 0.1 in2
Step 2: Write the formula and solve
P1=F1/A1 P2 = F2/A2
P1= 25 lbs/1 in^2 P2 = 5 lbs/0.01 in^2
P1 = 25 psi P2 = 500 psi
U3f – L3
The diagram below illustrates how hydraulic brakes in a car work. The pedal must be pressed with a force of 10 lbs. The surface area of the piston connected to the pedal is 1 square inch. If the surface area of the piston connected to the other end of the brake line is 2.5 square inch, what is the force applied to that piston?
P1 = P2
Problem 18
P1 = F1 / A1 P2 = F2 / A2
U3f – L3
Problems
Solution:Step 1: Write given information
P1 = ? P2 = ?
F1 = 10 lbs. F2 = ?
A1 = 1 in2 A2 = 2.5 in2
Step 2: Write the formula and solve for the unknowns
P1 = F1 / A1
P1 = (10 lbs) / (1 in2)
P1 = 10 psi
P1 = P2 = 10 psi
F2 = 10 psi x 2.5 in2 = 25 lbs.P2 = F2 / A2 F2 = P2 x A2
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