A 2 kg body is dropped from a height of 3 m. Calculate:
to. The speed of the body when it is 1 m high
b. The speed of the body when it reaches the ground
Question
Question
A 2 kg body is dropped from a height of 3 m. Calculate:
to. The speed of the body when it is 1 m high
b. The speed of the body when it reaches the ground
Answer:
a) 6.26 m/s
b) 7.67 m/s
Explanation:
The potential energy at height h0 is initially …
PE0 = mgh0
At height h1, the potential energy is …
PE1 = mgh1
The difference in potential energy is converted to kinetic energy:
PE0 -PE1 = KE1 = (1/2)m(v1)^2
Solving for v1, we have …
mg(h0 -h1) = (1/2)m(v1)^2
2g(h0 -h1) = (v1)^2
v1 = √(2g(h0 -h1))
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a) When the body is 1 m high, its speed is …
v = √(2(9.8)(3 -1)) ≈ 6.26 m/s . . . at 1 m high
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b) When the body is 0 m high, its speed is …
v = √(2(9.8)(3 -0)) ≈ 7.67 m/s . . . when it reaches the ground