Question

To lift a load of 100 N a distance of 1 m an effort of 25 N must be applied over an inclined plane of length 4 m. What must be done to lift the load 2 m, using the same effort? A.Use an inclined plane of length 8 m.
B.Use an inclined plane of length 2 m.

C.Use an inclined plane of length 10 m

D.Use an inclined plane of length 16 m.

Answer 1

Answer: The correct answer is A) Use an inclined plane of 8 m

Work :

Work is defined as force applied to an object to move it to some distance . It is calculated as product of force and displacement .

W = F* d

Where : W =work (N-m) F = force (N) d = displacement (m)

When a body is lifted , work can be expressed as :

W = m*g*h ( h = height )

Also force due to gravitation can be given as

F = m* g

where :

g = gravitational acceleration ($9.8 \frac{m}{s^2}$

Hence Work can be written as : W = F * h

Given :

Force on load due to gravitation = 100 N Height = 2 m

Force applied = 25 N displacement = ?

Work done to lift the load to 2 m = F * h

= 100 N * 2 m = 200 N-m

Plugging W = 200 N-m in work formula

W = F* d

200 N-m = 25 N * d

Dividing both side by 25 N

$\frac{200N-m}{25 N} = \frac{25 N * d}{25 N}$

d = 8 m

Hence, to lift the load using 25 N , the inclined plane of 8 m can be used .

Answer 2

The answer is A, use an inclined plane of length 8.