Question

A stone is released from a balloon that is descending at a constant speed of 10 m/s. Neglecting

air resistance, after 20 s the speed of the stone is:

A. 2160 m/s

B. 1760 m/s

C. 206 m/s

D. 196 m/s

E. 186 m/s​

Answer 1

Explanation:

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Answer 2

The final velocity of the stone = 206m/s. (Option - C)

Given: balloon descending at speed = 10m/s

           stone takes the speed of balloon - stone initial speed - u = 10m/s

           time - t = 20s

To Find: the speed of the stone - v =?

Solution:

Formula Used:

• Newton's first law of motion equation: v = u + gt( g - acceleration due to gravity = 9.8m/s²)
• As there is no air resistance, no horizontal acceleration, hence only vertical acceleration is considered.

Applying the above Formula:

v = u + gt

v = 10 + 9.8 × 20

v = 10 + 196

v = 206 m/s

Hence, after 20 s the final velocity of the stone = 206m/s. (Option - C)