{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

physics_ch7homework

# physics_ch7homework - Chapter 7 Homework 1 In one day a...

This preview shows pages 1–2. Sign up to view the full content.

Chapter 7 Homework 1. In one day, a 75-kg mountain climber ascends from the 1500-m level on a vertical cliff to the top at 2400 m. The next day, she descends from the top to the base of the cliff, which is at an elevation of 1350 m. What is her change in gravitational potential energy (a) on the first day = ( - ) ∆PE mg y2 y1 = . - 75 kg9 8 ms22400 m 1500 m = . × 6 62 105 J (b) on the second day? ∆PE = . - 75 kg9 8 ms21350 m 2400 m =- . × 7 72 105 J 2. A 5.00-kg sack of flour is lifted vertically at a constant speed of 3.50 m/s through a height of 15.0 m. (a) How great a force is required? = w mg = . . 5 00 kg9 8 ms2 = 49 N (b) How much work is done on the sack by the lifting force? What becomes of this work? = W Fs =( )( . ) 49 N 15 0 m = 735 J 3. A 120-kg mail bag hangs by a vertical rope 3.5 m long. A postal worker then displaces the bag to a position 2.0 m sideways from its original position, always keeping the rope taut.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 4

physics_ch7homework - Chapter 7 Homework 1 In one day a...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online