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An object of mass 40 kg is raised to a height of 5 m above the... - Science
An object of mass 40 kg is raised to a height of 5 m above the ground. What is its potential energy? If the object is allowed to fall, find its kinetic energy when it is half-way down.
1. Potential Energy (P.E.):
Given: Mass (m) = 40\text{ kg}, Height (h) = 5\text{ m}, g = 10\text{ m s}^{-2} (approx)
Formula:
P.E. = mghP.E. = 40 \times 10 \times 5 = 2000\text{ J}
2. Kinetic Energy (K.E.) half-way down:
At half-way height (h/2 = 2.5\text{ m}), the object has lost half of its potential energy, which is converted into kinetic energy.
Energy lost = \frac{2000}{2} = 1000\text{ J}
According to the Law of Conservation of Energy, this lost potential energy becomes kinetic energy.
Answer:
Potential Energy = 2000\text{ J} (assuming g=10\text{ m/s}^2, or 1960\text{ J} if g=9.8)
Kinetic Energy at half-way = 1000\text{ J} (or 980\text{ J})
