Question

a man of mass 70kg ascends a flight of 36 steps each 20cm high. Work done by the man against the gravitational force is (use g=9.8m/s2)
A)4932.2J
B)4000J
C)490J
D)4900J

Answer 1

Solution:

4932.2 J (Option-A)

Explanation:

Given:

→ A man of mass 70kg ascends a flight of 36 steps each 20cm high. work done by the man against the gravitational force is (g = 9.8 ms - 2).

Find:

→ Find the work done against gravitational force.

Calculations:

→ h = N × L

Know terms:

→ Height = Total number of steps × Length of the step.

Adding the values to the equation:

$\sf → h = 36 × (20 cm) \\ </p><p>\sf → 20 cm \\ </p><p>\sf → 0.2 m$

Adding values to the equation:

$\sf → h = 36 × 0.2 \\ </p><p>\sf → h = 72 × 10 {}^{ - 1} \\ </p><p>\sf → h = 7.2 m$

Work done: This is a formula:

→ W = Mgh

Know terms:

M = Mass of Body.

g = Acceleration because to Gravity.

h = Height of the Body.

Adding values to the Values:

$\sf → W = ( 70 × 9.8) × 7.2 \\ </p><p>\sf → W = ( 7 × 98) × 7.2 \\ </p><p>\sf → W = (686 × 7.2) \\ </p><p>\sf → W = 4939.2 J$

Therefore, 4939.2 Joules is the work done against gravitational force.

Answer 2

Explanation:

The first power loom was designed in 1786 by Edmund Cartwright and first built that same year. It was refined over the next 47 years until a design by the Howard and Bullough company made the operation completely automatic.