# Homework Help: Sunjamming question

1. Sep 11, 2008

### cgarr017

just wanted to double check with you on a webassign question. i feel like i'm doing it right but webassign doesn't like my answer... question 2 says A "sun yacht" is a spacecraft with a large sail that is pushed by sunlight. Although such a push is tiny in everyday circumstances, it can be large enough to send the spacecraft outward from the Sun on a cost-free but slow trip. Suppose that the spacecraft has a mass of 1100 kg and receives a push of 17 N.

(a) What is the magnitude of the resulting acceleration?

17/1100= 0.015 or 1.5e-2 but webassign says its wrong

(b) If the craft starts from rest, how far will it travel in 1 day?

change in x=vo(change in t)+1/2a(change in t)^2

=1/2(0.015)(24)(3600)^2

=5.6e7

(c) How fast will it then be moving?

but then again if the acceleration magnitude is wrong then part b equation wouldn't work. i'm also unsure how to do part c. let me know your thoughts. thanks

2. Sep 11, 2008

### Dick

Re: sunjamming

That looks fine. The only problems could be significant figures, or, did you put the correct units on the numbers? For c) you know the constant acceleration and you know the time. v=a*t??

3. Sep 11, 2008

### cgarr017

Re: sunjamming

ok thanks c did work but a and b is really frustrating me. the two given numbers in the problem were 1100kg and 17 N. so the sig figs should be 2 right? and the units is m/s^2
...(a) What is the magnitude of the resulting acceleration?
1.5e-2 m/s2 X wrong
(b) If the craft starts from rest, how far will it travel in 1 day?
5.6e7 m X wrong
(c) How fast will it then be moving?
1335 m/s correct
??????????

4. Sep 11, 2008

### Dick

Re: sunjamming

Well, I'm convinced you're right, and you're convinced you're right. You might want to try keeping extra decimal places in the acceleration. For example, I get 5.768E7m for the distance. You should probably only apply the rounding at the end. Not to intermediate numbers.

5. Sep 11, 2008

### cgarr017

Re: sunjamming

cool thanks anyway for your help

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