Question

a ball which is thrown vertically upwards rises to a height of 20m, calculate...

1. the velocity with which the ball is thrown upwards.

2. the time taken by the ball to reach the highest point (g=10m/s^-2)
​

Answer 1

hope it helps you mate.

please thank and Mark my answer as brainliest.

@ ANUSHA ❤✌

Answer 2

Answer

1 . Initial velocity , u = 20 m/s

2 . Time , t = 2 s

Given

• A ball which is thrown vertically upwards rises to a height of 20 m

To Find

1 . The velocity with which the ball is thrown upwards.

2 . the time taken by the ball to reach the highest point (g=10 m/s²)

Concept Used

We need to use equations of motion .

• v = u + at
• s = ut + ¹/₂ at²
• v² - u² = 2as

Solution

Height , s = 20 m

Here ball is thrown vertically upwards . So , at certain height the ball will go to rest . So ,

Final velocity , v = 0 m/s

Acceleration , a =  g = - 10 m/s² [ Thrown against the gravity ]

Now , apply 3rd equation of motion .

⇒ v² - u² = 2as

⇒ 0² - u² = 2 ( - 10 ) ( 20 )

⇒ - u² = - 400

⇒ u² = 400

⇒ u = 20 m/s

1 . Initial velocity , u = 20 m/s

_______________________

Use 1st equation of motion .

⇒ v = u + at

⇒ 0 = 20 + ( - g ) t\\

⇒ 0 = 20 - 10t

⇒ 10t = 20

⇒ t = 2 s

2 . Time taken to reach the highest point , t = 2 s

__________________________