Q. 40

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Found in: Page 156

### Physics for Scientists and Engineers: A Strategic Approach with Modern Physics

Book edition 4th
Author(s) Randall D. Knight
Pages 1240 pages
ISBN 9780133942651

# Henry, whose mass is 95 kg, stands on a bathroom scale in an elevator. The scale reads 830 N for the first 3.0 s after the elevator starts moving, then 930 N for the next 3.0 s. What is the elevator’s velocity 6.0 s after starting?

The velocity of the elevator after is downward.

See the step by step solution

## Step 1: Given information

Henry's mass-

The scales reads for the first after the elevator starts moving, then for the next

## Step 2: Calculation of elevator velocity

We know that, According to Newton's second law,

From this;

Writing equation of motion,

substituting in

Now, Before starting assuming

After starting The net force

Therefore, substituting the values of initial velocity and net force on we get

Now after interval the net force .

For final velocity after substitute in eq. 3.

Summing and

Velocity containing negative value is downward which means, the elevator is moving down or descending.