Question

3. An object is thrown vertically upward with a velocity of 10 m/s. It strikes the ground after ________seconds. (Take g=10 m ) ​

Answer 1

If we use S = ut + 1/2 at²

• so S will be zero because body moves up and comes down at same position ..so displacement will be zero .
• Initial velocity in upward direction will be +ve.
• Acceleration due to gravity will be -ve . ( downward ) .

___________

0 = 10 + 1/2 ( -10 ) t²

0 = 10 + (-1/2 ) × 10 t²

5 t ( 2 - t ) = 0

t = 0 or 2 - t = 0

t = 2 seconds

• body will at same position means displacement = 0

t = 0 ( initial position)

t = 2 sec.

After 2 seconds body will locate same position

therefore , It strikes the ground after 2 seconds.

hope it helps you..