A ball is thrown horizontally from the top of tower100 m high, with sp

1.	A ball is thrown horizontally from the top of tower100 m high, with speed 10 m/s. After 2 seconds offall, gravity disappears. Then total time taken by ballto reach the ground is (g = 10 m/s2)
Answer» Answer: Total time taken by the BALL to REACH the ground = 6 seconds Time taken by the ball to reach the ground after the gravity disappears = 4 seconds Explanation: GIVEN, The height of the tower = 100 m Initial horizontal SPEED = 10 m/s Ball is thrown horizontally from the top of the tower therefore its initial vertical speed will be zero Thus using the second equation of motion The vertical distance h covered in 2 seconds $\boxed{h=\frac{1}{2}gt^2}$ or, $h=\frac{1}{2}\times 10\times 2^2=20$ m Therefore the height left = 100 - 20 = 80 m The vertical VELOCITY after 2 seconds using the first equation of motion $v=0+gt$ $\implies v=10\times2=20$ m/s Since the gravity disappears after 2 seconds therefore there will be no acceleration in the vertical direction time taken to cover 80 m distance = distance/velocity = 80/20 = 4 seconds Therefore, total time taken by the ball to reach the ground = 2 + 4 = 6 seconds

A ball is thrown horizontally from the top of tower100 m high, with speed 10 m/s. After 2 seconds offall, gravity disappears. Then total time taken by ballto reach the ground is (g = 10 m/s2)

Answer»

Answer:

Total time taken by the BALL to REACH the ground = 6 seconds

Time taken by the ball to reach the ground after the gravity disappears = 4 seconds

Explanation:

GIVEN,

The height of the tower = 100 m

Initial horizontal SPEED = 10 m/s

Ball is thrown horizontally from the top of the tower therefore its initial vertical speed will be zero

Thus using the second equation of motion

The vertical distance h covered in 2 seconds

$\boxed{h=\frac{1}{2}gt^2}$

or, $h=\frac{1}{2}\times 10\times 2^2=20$ m

Therefore the height left = 100 - 20 = 80 m

The vertical VELOCITY after 2 seconds

using the first equation of motion

$v=0+gt$

$\implies v=10\times2=20$ m/s

Since the gravity disappears after 2 seconds

therefore there will be no acceleration in the vertical direction

time taken to cover 80 m distance = distance/velocity

= 80/20 = 4 seconds

Therefore, total time taken by the ball to reach the ground = 2 + 4 = 6 seconds