Lots of problems with UNITS

  • Thread starter gcombina
  • Start date
  • #1
157
3
Hello, I am having lots of problems with units. I don't know why but I am getting sick of it. I don't know what am I doing wrong.

Let me give you an example.

I have this problem:
A football player kicks a 0.41-kg football initially at rest; and the ball flies through the air. If the kicker's foot was in contact with the ball for 0.51 s and the ball's initial speed after the collision is 21 m/s, what was the magnitude of the average force on the football?

My attempt:

F = mv/t
F = (0.41 kg) (21m/s) / 0.051s
F = (8.61 Kg. m. / s) / 0.051 s
F = (8.61 kg.m) / 0.051 s^2
F = 169 kg.m/s^2

why is my unit so wrong??? (kg.m/s^2) (my answer should be in NEWTONS)
 

Answers and Replies

  • #3
157
3
of course :redface:

i think I need a break

Thanks!
 

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