Question

A 2 kg ice cube is released from point A and slides on a frictionless track as shown in the figure. Determine the speed of the cube at points B and C.

Answer 1

According to the conservation of energy

• Potential energy at any given instance is equal to the Kinetic energy as energy can neither be created nor be destroyed

Mass is 2kg=m

#A

h=5m

• PE=mgh

PE

• 2(9.8)(5)
• 10(9.8)
• 98J

Now

• KE=98J
• 1/2mv²=98J
• 1/2×2v²=98J
• v²=98J
• v=√98
• v=9.4m/s

#B

h=3.2m

PE:-

• 2(3.2)(9.8)
• 6.4(9.8)
• 62.7J

Now

• KE=62.7J
• 1/2mv²=62.7
• v²=62.7
• v=√62.7
• v=7.9m/s

#C

h=2m

PE

• 2(2)(9.8)
• 4(9.8)
• 39.2J

Now

• v²=39.2
• v=√39.2
• v=6.3m/s