A small ball with a mass of 4.1 kg moves along with the energy curve shown to th
ID: 1437129 • Letter: A
Question
A small ball with a mass of 4.1 kg moves along with the energy curve shown to the left, while not being subjected to any non-conservative forces. At point B it has a velocity of 2.7 m/sec.
1. What is the mechanical energy of the object at point B? MB =
2. What is the mechanical energy of the object at point A?MEA=
3. What is the mechanical energy of the object at point D? MED=
4. What is the net work done by conservative forces on the object between points B and C? WconB-C=
5. What is the velocity of the object at point C?vC=
Explanation / Answer
Given,
m = 4.1 kg ; v = 2.7 m/s ;
No non conservative forces acting on the ball.
1)At point B, its ME will be:
ME = PE + KE = 2 + 1/2 x 4.1 x 2.7 x 2.7 = 16.9 = 17 J
ME(B) = 16.9 = 17 J(Aprox)
2)ME(A) = 17 J ; Since No non conservative forces are acting, the value of ME has to be same at the given points. The increase/decrease in PE or KE will be compensated by one another.
3)ME(D) = 17 J, same explanation as 2.
4)Work done by the conservative forces = change in mechanical energy. But it did not change, So the net work done is zero.
5) ME = PE + KE
17 = 5 + 0.5 x 4.1 x Vc2
Vc = 2.42 m/s
Hence, velocity at point C is Vc = 2.42 m/s