A ball is thrown vertically upwards with a velocity of 20 m s-1 from t...
Taking vertical upward motion of the ball upto highers point
Here, u = 20 ms
-1v = 0 (at highest point velocity is zero)
a = -g = -10ms
-2As v
2 = u
2 + 2as
0 = (20)
2 + 2(-10)(S) or

A ball is thrown vertically upwards with a velocity of 20 m s-1 from t...
Understanding the Problem
A ball is thrown upwards with an initial velocity (u) of 20 m/s from a height of 25 m. We are to determine how high the ball will rise above the ground.
Key Concepts
- The maximum height (h) reached by the ball can be calculated using the kinematic equation:
h = u2 / (2g)
- Where:
- u = initial velocity (20 m/s)
- g = acceleration due to gravity (10 m/s2)
Calculating Maximum Height
1. Using the Kinematic Equation:
- Substitute the values:
- h = (20 m/s)2 / (2 * 10 m/s2)
- h = 400 m2/s2 / 20 m/s2
- h = 20 m
2. Total Height from the Ground:
- The total height from the ground when the ball reaches its maximum height is:
- Total height = Height of building + Maximum height reached by the ball
- Total height = 25 m + 20 m = 45 m
Conclusion
The ball will rise an additional height of 20 m above the building's top. So, the maximum height reached by the ball above its starting point (the building) is 20 m.
Thus, the correct answer is option 'C': 20 m.