Newton's Laws pulley homework

  • #1

Homework Statement



The 100 kg blcok in the figure takes 5.40 s to reach the floor after being released from rest. What is the mass of the block on the left?
knight_Figure_08_33.jpg


Homework Equations


F=ma
sf=si + (1/2)(a)(delta t)


The Attempt at a Solution



I know to find acceleration you use
sf=si + (1/2)(a)(delta t)
0=1+(1/2)(a)(5.4)
a = 0.0686 m/s2

and then the F=ma to find the force on the block of known mass.
F=(100 kg)(0.0686)
F=6.86

but from this I am not sure how to determine the mass of the block on the left?
 

Answers and Replies

  • #2
tiny-tim
Science Advisor
Homework Helper
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Welcome to PF!

a = 0.0686 m/s2

and then the F=ma to find the force on the block of known mass.
F=(100 kg)(0.0686)
F=6.86

but from this I am not sure how to determine the mass of the block on the left?
Hi redlightgreen! Welcome to PF! :smile:

Find the tension, T, and then use the fact that the block on the left has the same acceleration (in the opposite direction, of course). :wink:
 
  • #3
oh okay! thank you so much.
i've got it now!
 

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