I have been given the question below and I know where to go with it but just not sure on how to go about it. When you lift a bowling ball with a force of 80 N, the ball accelerates upward with an acceleration a. If you lift with a force of 89 N, the ball's acceleration is 2a. I know to use F=ma rearranged to m=F/a then put the first set of data = to the second set giving 80/a=89/2a. From this point I'm not sure how to solve for a. I have tried doing a bit of algebra but haven't been able to get it down to one a and be able to solve. Any help on this would be much appreciated. Chris
You forgot the mass of the ball when resolving the force. The upwards force isn't 80, it's (80-m). Simlarly it's (89-m) for the second ball. Code: So for the first ball a = (80-m)/m (eqn 1) Second ball 2a = (89-m)/m (eqn 2) Multiply (eqn 1) by 2: 2a = 2(80-m)/m (eqn 3) Equate (eqn 3) and (eqn 2): (89-m)/m = 2(80-m)/m Multiply through by m (89-m) = 2(80-m) 89 - m = 160 - 2m m = 160-89 m = 71 Sub value of m into (eqn 1) to find a
Thanks, I sort of forgot about taking into account the mass of the ball. A couple attempts I had were very close (0.02 off) using a different method but the website on which it is submitted to is a bit picky about rounding and for some reason would not accept it. Even when doing it exactly as written above i had 2 manually change the value to 72 for it to accept due to the rounding for the answer.
