Advertisements
Advertisements
Question
A fixed pulley is driven by a 100 kg mass falling at a rate of 8.0 m in 4.0s. It lifts a load of 75.0 kgf. Calculate the power input to the pulley taking the force of gravity on 1 kg as 10 N.
Solution
Load = 75.0 kgf
Mass of falling object = 100 kg
Displacement of effort = 8.0 m
Time taken = 4.0s
Effort = 100 × 10 = 1000 kgf
Power Input
`"P"_"in" = "displacement × effort"/"time"`
= `(8 ×1000)/4`
= 2000 W
APPEARS IN
RELATED QUESTIONS
A gear system has the driving wheel of radius 2 cm and driven wheel of radius 20 cm.
(a) Find the gear ratio.
(b) If the number of rotations made per minute by the driving wheel is 100, find the number of rotations per minute made by the driven wheel.
(c) If the driven wheel has 40 teeth, find the number of teeth in the driving wheel.
A Woman draws water from a well using a fixed pulley. The mass of bucket and water together is 6 kg. The force applied by the woman is 70 N. Calculate the mechanical advantage. (Take g = 10 m s-2)
In a block and tackle system consisting of 3 pulleys, a load of 75 kgf is raised with an effort of 25 kgf. Find:
- the mechanical advantage,
- velocity ratio and
- efficiency.
In following figure, draw a tackle to lift the load by applying the force in the downward direction.
- Mark in the diagram the direction of load L and effort E.
- If the load is raised by 1 m, through what distance will the effort move?
- State how many strands of tackle are supporting the load?
- What is the mechanical advantage of the system?
A block and tackle system has the velocity ratio 3. Draw a labelled diagram of the system indicating the points of application and the directions of load L and effort E. A man can exert a pull of 200 kgf. What is the maximum load he can raise with this pulley system is its efficiency is 60%?
A pair of nut crackers is 12 cm long. An effort of 10 gf is required to crack a nut which is passed at a point 3 cm from the finger. Calculate the load Fig.
A fixed pulley is driven by a 100 kg mass falling at a rate of 8.0 m in 4.0 s. It lifts a load of 75.0 kgf. Calculate the efficiency of the pulley.
A fixed pulley is driven by a 100 kg mass falling at a rate of 8.0 m in 4.0 s. It lifts a load of 75.0 kgf. Calculate : the height to which the load is raised in 4.0 s.
The mechanical advantage of a machine is 5 and its efficiency is 80%. It is used to lift a load of 200 kgf to a height of 20 m. Calculate:
(i) The effort required, and
(ii) The work done on the machine (g = 10 ms−2).
