Physics

Vandebilt Catholic High School

W. Dupre

Work-Energy Theorem – Answers to Level 1 Worksheet

 

28]       33.75 J; 135 J

 

29]       60 J; 60 J

 

31]       vf = (2W/m)1/2 ;  F = mvf2/2d

 

33]       650 J;  -588 J;   0 J;  0 J;  62 J;  1.76 m/s

 

38]       4.1 X 10-18 J;   1.14 X 10-17 N;  1.25 X 1013 m/s2;  2.4 X 10-7s

 

41]       0.79 m/s;         0.53 m/s

 

75]       K = (2 + 24t2 + 72t4)J;            a = 12t m/s2;               F = 48t N;

            P = 48t + 288t3                        W = 1250 J

 

77]       20 J;   6.71 m/s

 

 

 

NOTE to Rebecca T. we must use the derivative of Work/Energy to determine the power in #75 because the question asks for instantaneous power (“the power being delivered to the particle at time t”). If we simply did P = K/t we would be solving for the average power delivered to the particle during that time interval and not the instantaneous power. Using P = F•v works because both the “F” and “v” values used are instantaneous values.

I hope this clears it up for you.