really need help, i have no idea how to answer this question !
A stone is thrown off a cliff. it reaches a maximum height of 30m after 2 seconds, then falls into the water below. it hits the water after 5 seconds
a) how high above the water is the cliff ( The maximum height is relative to water level )
b) what is the ' second zero' and what does it mean
No problem! I'll explain how to answer the two questions step by step:
a) To determine the height of the cliff above the water level, we need to consider the stone's motion. We know that the stone reaches its maximum height of 30m after 2 seconds and hits the water after 5 seconds.
First, let's calculate the total time the stone spends in the air. It goes from the initial throw until it hits the water, which is a duration of 5 seconds.
Next, we can divide this total time into two parts: the time it takes to reach the maximum height and the time it takes to fall back down. Since the maximum height is reached after 2 seconds, the remaining time until it hits the water is 5 - 2 = 3 seconds.
During the upward part of the stone's motion, it follows a parabolic path. The time it takes to reach the maximum height is half the total time in the air (2 seconds), as a thrown projectile reaches its maximum height halfway through its journey.
Now, we can calculate the vertical distance covered during the upward part of the motion. We can use the formula for vertical displacement (d) in free-fall motion:
d = (1/2) * g * t^2
Where g is the acceleration due to gravity (approximately 9.8 m/s^2) and t is the time. Plugging in the values, we find:
d = (1/2) * 9.8 * (2)^2 = 19.6 m
Therefore, the cliff is 19.6 meters above the water level.
b) The "second zero" refers to the time when the stone hits the water. It is called the "second zero" because we usually consider the first zero as the initial throw or launch. In this case, the first zero is when the stone is thrown off the cliff and the second zero is when it hits the water.
So, the "second zero" is 5 seconds, and it represents the time at which the stone reaches the water.
I hope this explanation helps you answer the questions!