Help with Newtons Second Law Question Please.

[123tricks]

Homework Statement

Calculate the force needed to accelerate a 2.0kg ball at 3.0ms^2

(A) In space, a long way from Earth.
(B) On a frictionless horizontal surface, near the surface of the earth.
(C) vertically upward, near the surface of the earth.

Homework Equations

F = m*a

The Attempt at a Solution

(A) F = 2.0 * 3.0
F= 6N?

(B) Same as above?

(C) I am confused on this one.

Would it be F = m*a

F = 2.0 *(9.8 - 3.0)
F= 2.0 * 6.8
F= 13.6N?

or

F = 2.0 * 12.8 (To get from -9.8 to 3 = 12.8)
F= 24.8N

If those answers are wrong could anyone point me in the right direction as to what I am doing wrong?

Thanks.

 

[Chewy0087]

Edit: Aha, check your final line, you sure That 2 * 12.8 = 24.8? 0.o

First two are fine

 

[123tricks]

Edit: Aha, check your final line, you sure That 2 * 12.8 = 24.8? 0.o

First two are fine

Ahaha... I mean 25.6 :)

 

[Chewy0087]

thats right