Radians
DOUBLE POINTS!
360° = ______radians
6.28
360° =_____π
2
DOUBLE POINTS!!
What is the equation for work?
Force X Distance
Find the torque: A mechanical winch is being used to pull a car out of the ditch. If the crank handle is 1.5 ft long and it requires 15.5 lb of force to turn it.
Torque= 1.5 ft X 15.5 lb= 23.25 ft-lb
DOUBLE POINTS!!
How are automobiles measured in efficiency?
MPG
90° = ______radians
1.57
180° =_____π
1
What is the equation for torque?
Force x Lever
A simple mechanical winch has a crank handle one foot long. A force of 20 lb is required to turn the crank.
Find: How much work is done in turning the crank through five revolutions?
T= 20ft-lb
Then find the total angle of revolutions in radians:
𝜃= 5 revolutions (2𝜋)
𝜃= 10𝜋 radians
Now find the work done: Work= Torque x Angle (𝜃)
W=(20 lb-ft) x (10𝜋).
W= (20 lb-ft) x (10) x (3.14)
W= 628 lb-ft or 628 ft-lb
What does it mean to be efficient?
To do something well, in a timely matter with little to no mistakes
TRIPLE POINTS!!
45° = _______ radians
0.785
90°= ______π
0.5
True or False. The equation for efficiency is Input/Output x 100.
False
An electric motor is use to drive a water pump. The motor provides a torque of 150 Nm.
Find: How much work is done while the motor turns through 50 revolutions
47,100 ft-lb
How can you tell something is input work?
Input work is the work YOU or a person put into a system
180° = ____ radians
3.14
45° = _____π
0.25
What is the equation for efficiency?
(Output/Input) X 100
A simple mechanical winch has a crank handle two foot long. A force of 35 lb is required to turn the crank. How much work is done in turning the crank through 20 revolutions?
Torque = 70 ft-lb
Radians= 40 pi
Work= 8,792 ft-lb
How can you tell something is output work?
Output work is the object that moves because of the input
Find the radians. I have a water pump to irrigate my lawn, in pi, how many radians would it be if the pump turned through 250 revolutions?
500 π
270° =_____π
1.5
How do solve for work that uses revolutions/rotations in the problem
Multiply Torque & Radians
DOUBLE POINTS!!
Brian has a small hobby farm he uses a 4 pulley block and tackle to lift small square bales of hay into the loft. The loft is 12 ft. off the floor of the barn and he has to clear the loft by 2 feet to get the bales onto it. If he pulls the rope with 50 kg of force and moves 40 ft of rope. Determine the input work that Brian did on the pulley system in ft-lb. If his hay bales weigh 130 lb, determine the work he did on each bale in ft-lb. Determine the efficiency of the pulleys.
Input= 4400 ft-lb
Output= 1820 ft-lb
Efficiency= 41.36%
George is using a winch to pull open a cattle guard and clean it. The winch on his pickup has a torque of 200 Nm. If the winch goes through 15 revolutions, how much work is being done to lift the cattle guard?
18,840 Nm