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# help with physical science questions

Asked May 25, 2012, 04:26 PM — 2 Answers
The amount of power measured for a 120 lb person running up 10ft (w = 1200 lb x ft) of stairs over a 6 second time frame is

2 Answers
 Thato maine Posts: 1, Reputation: 1 New Member #2 Jun 26, 2012, 07:45 PM
A box rests at the bottom of a 30degree inclined plane. A constant force of 245N moves the box at constant speed 5m higher up the smooth plane. What is the weight of the box ?
 ebaines Posts: 10,136, Reputation: 5589 Expert #3 Jun 27, 2012, 06:11 AM
Quote:
 Originally Posted by squirrel_1 The amount of power measured for a 120 lb person running up 10ft (w = 1200 lb x ft) of stairs over a 6 second time frame is
Power is equal to work per unit time. You already know the work done - so simply divide by the time takesn to get power in terms of lb-ft/second.

Quote:
 Originally Posted by Thato maine A box rests at the bottom of a 30degree inclined plane. A constant force of 245N moves the box at constant speed 5m higher up the smooth plane. What is the weight of the box ?
Thato - please don't tag a new question onto an old thread, but rather you should post a new question.

The force applied to the box must counteract the weight of the box in order for it to move at constant velocity - meaning no acceleration so the sum of forces acting on the box =ma = 0. Can you tell us the component of the box's weight resisting movement in the direction of the inclined plane? This must equal the force being applied - then you can set up a equation and solve for 'm'.

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