Question

A person standing at the edge of a seaside cliff kicks a stone over the edge with a speed of 12 m/s. The cliff is 45 m above the water’s surface. With what speed does the stone strike the water? a) 42 m/s b) 48 m/s c) 54 m/s d) 60 m/s

Answer 1

The stone strikes the water with a speed of 54 m/s. Option C is answer.

Step-by-step explanation:

The stone is initially only moving horizontally, but as it falls, it also gains a vertical velocity due to gravity. The vertical velocity of the stone just before it hits the water can be calculated using the following equation:

v² = u² + 2as

where:

v is the final velocity (just before hitting the water)

u is the initial velocity (horizontal)

a is the acceleration due to gravity (9.8 m/s²)

s is the displacement (vertical distance)

Plugging in the values we know, we get:

v² = 12² + 2(9.8)(45)

Solving for v, we get:

v = 54 m/s

Therefore, the stone strikes the water with a speed of 54 m/s. Option C is answer.