physics question need some help?

Question

a fully dressed astronaut, weighing 1.2 x 10^3 N on earth is about to jump down from a space capsule that has just landed safely on Planet X. The drop to the surface of X is 2.8 m and the astronauts gravitational potential energy relative to the surface is 1.1 x 10^3 J.

a) what is the magnitude of the gravitational field strength on planet X.
b) how long does the jump take?
c) what is the astronauts maximum speed?

thanks for any help.......

and how do you convert 333660.6 J to scientific notation?

Answer 1

The question asked for "gravitational field strength" so Nkg^-1 is the correct unit.

Answer 2

Mastermind's work was good ... except he left you with stange units for g on planet X. g=3.208333333 NKg^-1

From F = m*a and a bit of algebra you can see that
1 NKg^-1 = 1 m/s^2

and how do you convert 333660.6 J to scientific notation? I think typically with scientific notation you want the decimal just after the first digit. Count how many places you have to move it to get it there. In this case, 5 places to the left. You're making the number smaller when you move the decimal left.
So choose the exponent on 10 to cancel that out.

3.336606 * 10^5 J

Sometimes it's convenient to make the exponent on 10 a multiple of 3. If that's what you want to do, change it either of these ways and then use the K or M prefix on Joules.

333.6606 * 10^3 J = 333.6606 KJ (kiloJoules)
or
0.3336606 * 10^6 J = 0.3336606 MJ (megaJoules)

Answer 3

a) G.P.E = mass X gravity acc . height .
1.1X10^3 = (1.2*10^3/9.8) XgX2.8
g=3.208333333 NKg^-1

b) s=1/2at^2
2.8=1/2(3.208333333)t^2
t=1.321156519 s.

c) V^2=2as+u^2
V^2=2(3.208333333)(2.8)
V=4.238710494 ms^-1