Question

A block and tackle has a velocity ratio of 4 and it is used to vertically raise a load of mass 50kg.if the effciency is 80%,determine the minimum effort reguired to raise the load.

Answer 1

Velocity ratio (V.R) is:

distanced moved by effort / distance moved by by load

Mechanical Advantage (M.A)
=Load/Effort

Efficiency = M.A/V.R

In the problem:
Velocity Ratio = 4
Efficiency = 0.80
Load = 50kg * 9.81m/s^2 = 490.5N

Using the formula:
Efficiency = M.A / V.R


=> .80 = M.A / 4
=> M.A = 3.2

Now,

M.A = Load/Effort

3.2 = 490.5 / Effort

Effort ?

Answer 2

-487.3

Answer 3

487.3

Answer 4

153.28

Answer 5

_143

Answer 6

493.7

Answer 7

153.28

Answer 8

156.25