Homework Answers
a) While lifting the weight and to keep it moving up with constant velocity he has apply the force of mg upwards . If the displacement is d in the upwards direction then the work done by him is + mgd
b) while lowering the weight the gravitational force will try to accelerate the weight downwards , in order to keep it moving downwards with a constant speed he has to apply the mg force in the upwards direction while the displacement is happening in the downwards direction . Hence the work done by him will be - mgd.
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The weight is raised and lowered at a constant velocity. Determine the work done on the...
A weight lifter is bench-pressing a barbell whose weight is 710 N. He raises the barbell...
A weight lifter is bench-pressing a barbell whose weight is 710 N. He raises the barbell a vertical distance of 0.65 m, and then lowers it back to its original position next to his chest. Assume the weight is raised and lowered at a constant velocity, and that “up” is the positive direction. Determine the work done on the barbell (a) While the barbell is being raised (b) While the barbell is being lowered
5) A weight lifter lifts a mass of 50 kg barbell from the floor to a...
5) A weight lifter lifts a mass of 50 kg barbell from the floor to a height of 0.5 meter. 5a) Calculate the work done by the weight lifter on the barbell 5b) Calculate the work done by the gravitational force.
Determine the work done by you in the following situations. A) Pulling horizontally with a force...
Determine the work done by you in the following situations. A) Pulling horizontally with a force of 20 N on a 100 N sled. Sled moves 2 m at a constant velocity. (include units with answer) B) Pulling horizontally with a force of 40 N on a 100 N sled. Sled moves 2 m at a constant acceleration. (include units with answer) C) Pushing at 30° from horizontal with a force of 40 N on a 100 N sled. Sled...
In exercising, a weight lifter loses 0.174 kg of water through evaporation, the heat required to...
In exercising, a weight lifter loses 0.174 kg of water through evaporation, the heat required to evaporate the water coming from the weight lifter's body. The work done in lifting weights is 1.40E+5 J. Assuming that the latent heat of vaporization of perspiration is 2.40E+6 J/kg, find the change in the internal energy of the weight lifter.
In exercising, a weight lifter loses 0.124 kg of water through evaporation, the heat required to...
In exercising, a weight lifter loses 0.124 kg of water through evaporation, the heat required to evaporate the water coming from the weight lifter's body. The work done in lifting weights is 1.44E+5 J. Assuming that the latent heat of vaporization of perspiration is 2.41E+6 J/kg, find the change in the internal energy of the weight lifter.
Compute the work done by lifting a weight at the gym: lift 10kg, 1m, ten times....
Compute the work done by lifting a weight at the gym: lift 10kg, 1m, ten times. What is the change in energy after your workout?
A weightlifter stands up at constant speed from a squatting position while holding a heavy barbell...
A weightlifter stands up at constant speed from a squatting
position while holding a heavy barbell across his shoulders.
a) Draw a free-body diagram for the barbell.
Draw the vectors starting at the black dots. The location and
orientation of the vectors will be graded. The length of the
vectors will not be graded.
B) Draw a free-body diagram for the weight
lifter. Draw the vectors starting at the black dots. The location
and orientation of the vectors will be...
You are moving into an apartment and take the elevator to the 6th floor. Suppose your...
You are moving into an apartment and take the elevator to the 6th floor. Suppose your weight is 730 N and that of your belongings is 980 N. (a) Determine the work done by the elevator in lifting you and your belongings up to the 6th floor (15.2 m) at a constant velocity. (b) How much work does the elevator do on you alone (without belongings) on the downward trip, which is also made at a constant velocity?
answer both Question 2. Determine the work done in lifting a 100 kg block vertically 500...
answer both
Question 2. Determine the work done in lifting a 100 kg block vertically 500 cm. Question 3. A gas engine supplies a torque of 3 kN-m for 400 revolution. Determine the shaft work done by the engine.
1. An electrically driven screw-press is shown. The "load-bar" is raised or lowered via two threaded...
1. An electrically driven screw-press is shown. The "load-bar" is raised or lowered via two threaded screws supported via collar-bearings. Each screw is a 20mm diameter and 4mm in pitch with single square threaded. The collars each have an effective diameter of 30mm. The thread coefficients of friction is 0.075 and 0.095 for the screw and collar respectively. Each screw supports a load of 6kN. a) Find the torque required (per screw) to raise or lowerthe bar b) Determine if...
A weightlifter stands up at constant speed from a squatting
position while holding a heavy barbell across his shoulders.
a) Draw a free-body diagram for the barbell.
Draw the vectors starting at the black dots. The location and
orientation of the vectors will be graded. The length of the
vectors will not be graded.
B) Draw a free-body diagram for the weight
lifter. Draw the vectors starting at the black dots. The location
and orientation of the vectors will be...
answer both
Question 2. Determine the work done in lifting a 100 kg block vertically 500 cm. Question 3. A gas engine supplies a torque of 3 kN-m for 400 revolution. Determine the shaft work done by the engine.
1. An electrically driven screw-press is shown. The "load-bar" is raised or lowered via two threaded screws supported via collar-bearings. Each screw is a 20mm diameter and 4mm in pitch with single square threaded. The collars each have an effective diameter of 30mm. The thread coefficients of friction is 0.075 and 0.095 for the screw and collar respectively. Each screw supports a load of 6kN. a) Find the torque required (per screw) to raise or lowerthe bar b) Determine if...
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