Monday

April 21, 2014

April 21, 2014

Posted by **Elisabeth** on Saturday, June 5, 2010 at 9:31pm.

(I know the answers to B and C, I just have a question on A)

A) What is the change in the hikers potential energy?

I took PE=mg(h2-h1) and got (56.5)(9.8)(2660-1270)=769643J

When I checked my work with some problems on the net, I was seeing answers as large as mine and others that only used 4 digits (Like 7696J)

Why are they cutting them down, and shouldn't the unit change if they did? If the unit should change... why?

- Physics -
**MathMate**, Sunday, June 6, 2010 at 8:42amYour calculation looks good to me, except for the number of significant digits (too many) in the answer.

You may want to review the other answers on the net to see if

1. they use different units (hJ, kJ, etc.)

2. they use scientific notation, like 7696*10²J., thereby trimming on the number of significant digits.

Also, is the hiker's mass 56.5 or 56.6?

- Physics -
**Elisabeth**, Sunday, June 6, 2010 at 1:17pmJust a typo on my part. The hiker's mass is the same as in my equation: 56.5.

I just looked over the answers again. Most people answered the same as I did. A few of them put in scientific notation, but not like you did. they put 7.6X10^5 which doesn't make sense to me. I like your notation better. Fits the four digits. One person answered it in kJ, but the answer was only three digits long. I think I am going with the four digit scientific notation. It makes the most sense to me.

Thank you very much!

- Physics -
**MathMate**, Sunday, June 6, 2010 at 7:11pmI personally would suggest using powers of 10 that are multiples of three (some call it the engineering notation). This makes for easier interpretation, i.e. thousands, millions, billions, etc.

So

769643J

=769.6*10^3J

=769.6kJ

=0.770*10^6J

etc.

**Related Questions**

physics - A 55 kg hiker starts at an elevation of 1600 m and climbs to the top ...

Physics - A 67 kg hiker climbs to the top of a 3700 m-high mountain. The climb ...

physics - A 64 kg hiker climbs to the top of a 3700 m-high mountain. The climb ...

Physics - An 80 kg hiker climbs a 1000 m high hill at a constant speed. If the ...

Physics - When driving west toward the Rocky Mountains, you see a peak 3.0 above...

phsycis - A 62 kg hiker climbs to the top of a 3700 m-high mountain. The climb ...

physics - A hiker climbs a hill 300m high.If she weighs 50kg,calculate the work ...

math - from a base elevation of 8600ft a mountain peak in Colorado rises to a ...

Math Olympiad - Lara starts at the bottom of a long staircase. She climbs ...

Algebra 1A - From a base elevation of 8200 ft. a mountain peak in colorado rises...