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.

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 ?

153.28

-487.3

_143

493.7

153.28

156.25

To determine the minimum effort required to raise the load using a block and tackle, we can use the formula:

Efficiency = (output work / input work) * 100%

Efficiency is given as 80% (0.80), the velocity ratio is given as 4, and the mass of the load is 50 kg.

First, let's calculate the output work:

Output work = load * distance lifted

Since the block and tackle is used vertically, the distance lifted is the same as the height.

The weight of the load (force) can be calculated using:

Force = mass * acceleration due to gravity

Acceleration due to gravity is approximately 9.8 m/s^2.

Force = 50 kg * 9.8 m/s^2 = 490 N (Newtons)

Now, calculate the distance lifted:

Distance lifted = (Force * velocity ratio) / (mass * acceleration due to gravity)

Distance lifted = (490 N * 4) / (50 kg * 9.8 m/s^2) = 2 m

Next, we can determine the input work:

Input work = output work / efficiency

Input work = (Force * distance lifted) / efficiency

Input work = (490 N * 2 m) / 0.80 = 1225 Nm

Finally, to find the minimum effort required, we consider that the input work is equal to the effort (force) multiplied by the distance the effort acts over:

Effort * distance effort acts = 1225 Nm

Effort = 1225 Nm / distance effort acts

Since the question only gives the velocity ratio, we cannot directly determine the distance the effort acts. However, we can assume that each side of the block and tackle contributes equally to the distance effort acts.

Therefore, the distance effort acts can be calculated as the total distance lifted divided by the velocity ratio:

Distance effort acts = distance lifted / velocity ratio

Distance effort acts = 2 m / 4 = 0.5 m

Finally, we can calculate the minimum effort required:

Effort = 1225 Nm / 0.5 m = 2450 N (Newtons)

Therefore, the minimum effort required to vertically raise the load of 50 kg using a block and tackle with a velocity ratio of 4 and an efficiency of 80% is 2450 Newtons.

487.3