Question

Blocks I and II, each with a mass of 1.0 kg, are hung from the ceiling of an elevator by ropes 1 and 2.What is the force exerted by rope 1 on block I when the elevator is traveling upward at a constant speed of 2.0 m/s?What is the force exerted by rope 1 on block II when the elevator is stationary?

When a body in the elevator is hung then-
If the elevator is at rest the only its weight is acting on it,

a.If the elevator is moving upward with constant velocity the wight of the body will not change.
b.If the elevator is moving upward with constant acceleration the weight of the body will increase.
c.If the elevator is moving downward with constant velocity the weight of the body will remain the same.
d.If the elevator is moving downward with constant acceleration the weight of the body will decrease.

Answer 1

Answer:

Part a)

$T = 9.8 N$

Part b)

$T = 9.8 N$

Part c)

If elevator is accelerating upwards then we have

So tension will be more than the weight

Now if the elevator is moving with uniform velocity

tension will be equal to the weight of the block

Explanation:

Part a)

As we know that rope 1 is connected to block 1 at its lower end

So here we have elevator is moving at constant velocity in upward direction

so we have

$T - mg = 0$

$T = mg$

$T = 1\times 9.8$

$T = 9.8 N$

Part b)

now for block II we have

$T - mg = ma$

$T - mg = 0$

$T = 1 \times 9.8$

$T = 9.8 N$

Part c)

If elevator is accelerating upwards then we have

$T - mg = ma$

$T = mg + ma$

So tension will be more than the weight

Now if the elevator is moving with uniform velocity

$T - mg = 0$

$T = mg$

so tension will be equal to the weight of the block