a block and tackle has two pulleys in each block. It enables to lift a load of 100kgf with an effort of 30kgf. calculate mechanical advantage and efficiency.
Answers
Answer :
- Mechanical advantage of the pulley is 3.4
- Efficiency of the pulley is 170%.
Explanation :
Given :
- Load of the pulley, L = 100 kgf
- Effort applied on the load, L = 100 kgf
- Velocity ratio of the machine = No. of pulleys = 2
To find :
- Mechanical advantage of the pulley, M.A. = ?
- Efficiency of the pulley, E = ?
Knowledge required :
- Formula for mechanical advantage of a machine :
⠀⠀⠀⠀⠀⠀⠀⠀⠀M.A. = L/E⠀
[Where : M.A. = Mechanical advantage of the machine, L = Load on the machine, E = Effort applied on the load]
- Formula for efficiency of a machine :
⠀⠀⠀⠀⠀⠀⠀⠀⠀η = (M.A./V.R. × 100)%⠀
Solution :
To find the mechanical advantage of the machine :
⠀ By using the formula for mechanical advantage of a machine and substituting the values in it, we get :
⠀⠀=> M.A. = 100/30
⠀⠀=> M.A. = 10/3
⠀⠀=> M.A. = 3.4 (approx.)
⠀ ⠀ ⠀ ∴ M.A. = 3.4
⠀ Hence the mechanical advantage of the machine is 3.4.
To find the efficiency of the machine :
⠀ By using the formula for efficiency of a machine and substituting the values in it, we get :
⠀⠀=> η = (M.A./V.R. × 100)%
⠀⠀=> η = (3.4/2 × 100)%
⠀⠀=> η = (1.7 × 100)%
⠀⠀=> η = 170%
⠀ Hence the efficiency of the machine is 170%.
Answer:
MA = 3.33 and efficiency = 83.3%
Step-by-step explanation:
MA = L/E
efficiency = MA/VR
VR = 4(VR = number of strands of the tangle = number of pulleys)
therefore,
MA = 100/30 = 3.33
efficiency = 100/3/4 = 10/3 x 1/4 = 0.8333.... = 0.833 x 100 = 83.3%
Final answer:
MA = 3.33 and efficiency = 83.3%