A man is standing on the top of a 60 m high tower. He throws a ball ve...
Time for the ball to pass the man while going downwards:
To determine the time it takes for the ball to pass the man while going downwards, we need to analyze the motion of the ball.
Initial velocity: The ball is thrown vertically upwards with a velocity of 20 m/s.
Acceleration: The only force acting on the ball is gravity, which causes it to accelerate downwards. The acceleration due to gravity is approximately 9.8 m/s².
Final velocity: When the ball reaches its maximum height, its vertical velocity becomes 0 m/s. As it starts falling, its velocity increases in the downward direction.
Time to reach maximum height:
We can use the formula v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time taken.
0 = 20 - 9.8t
9.8t = 20
t = 20 / 9.8
t ≈ 2.04 seconds
Time for the ball to pass the man while going downwards:
The time it takes for the ball to reach the maximum height is equal to the time it takes for the ball to come down from the maximum height to the ground.
Therefore, the ball will pass the man while going downwards approximately 2.04 seconds after it was thrown.
Time for the ball to reach the ground:
To find the total time it takes for the ball to reach the ground, we need to consider the time it takes to reach the maximum height and the time it takes to come down from the maximum height.
The time to reach the maximum height is 2.04 seconds.
The total time to reach the ground can be determined using the equation s = ut + 1/2at², where s is the distance, u is the initial velocity, a is the acceleration, and t is the time taken.
Let's assume the total time to reach the ground is t_total.
Using the equation for the distance covered in free fall, -60 = 0 + 1/2(-9.8)t_total², as the initial velocity when the ball comes down is 0 m/s.
-60 = -4.9t_total²
t_total² = 60 / 4.9
t_total ≈ 3.06 seconds
Therefore, the ball will reach the ground approximately 3.06 seconds after it was thrown.
In summary, the ball will pass the man while going downwards approximately 2.04 seconds after it was thrown, and it will reach the ground approximately 3.06 seconds after it was thrown.
To make sure you are not studying endlessly, EduRev has designed Class 9 study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in Class 9.