Science, asked by guptahareram1973, 10 months ago

A bob is suspended from a spring balance in an elevator. The reading is 100 N when lift is at rest. If the spring balance reading now changes to 80 N, then the elevator is moving

(1)upwards with increasing. speed

(2)downwards with increasing speed

(3)downwards with decreasing speed

(4)downwards with constant speed​

Answers

Answered by johangeo71
3

Answer:

4 is your answer. Thank you

Answered by netta00
1

Answer:

(2)downwards with increasing speed

Explanation:

When lift is at rest reading is 100 N

mg = 100 N

Lets assume that elevator is moving up ward with acceleration a m/s².So the reading of spring balance ,S

S= mg + m a

S= 100 + m a

Given that

S= 80 N

80 = 100  - m a

m a = -20 N

It means that our assumption is wrong because we assume that acceleration is upward.But it comes out with negative sign .So we can say that elevator is moving downward.

When moving downward with acceleration a m/s²

S= mg - m a

80 = 100 - m a

m a = 20 N

Answer

(2)downwards with increasing speed

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