Question

An elevator weighing 2.5 10^4N is raised to a height of 10 meters. Neglecting friction, the work done is
A) 2.5 10^4 J
B) 2.5 10^5 J
C) 2.5 10^3 J
D) 7.5 10^4 J
E) 98 J

Answer 1

Answer on Question #45040, Physics, Other

Question:

An elevator weighing 2.5 10^4N is raised to a height of 10 meters. Neglecting friction, the work done is

A) 2.5 10^4 J

B) 2.5 10^5 J

C) 2.5 10^3 J

D) 7.5 10^4 J

E) 98 J

Answer:

The law of conservation of energy:

$$W = \Delta E$$

where $W$ is work, $\Delta E$ is change of energy.

The change of elevator's energy equals:

$$\Delta E = m g h = P h$$

where $m$ is mass, $h$ is height, $g$ is acceleration due to gravity, $P$ is weight.

Therefore:

$$W = P h = 2.5 \cdot 10^4 \cdot 10 = 2.5 \cdot 10^5 J$$

Answer: B) 2.5 10^5 J

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