Question

A body thrown vertically upwards from the top of a building in 5s if the body is thrown vertically downwards with the same velocity it will take only 2s to reach the foot of the building calculate the height of the building and the velocity with which it was thrown

Answer 1

Given:-

First Case:-

• Final Velocity of body = 0m/s ( As it was thrown upward )

• Time taken = 5s.

• Acceleration due to gravity = -10m/s

Second Case:-

• Time taken = 2s

• Acceleration due to gravity = + 10m/s

Extra Information:-

• In both Case they are thrown with same velocity.

To Find :-

• The Height of the Building and the Velocity with which it was thrown.

Formulae used:-

• v = u + at

• S = ut + ½ × a × t²

Now,

First Case:-

→ v = u + at

→ 0 = u + -10 × 5

→ -u = -50

→ u = 50m/s

Hence, The Initial Velocity of body is 50m/s

It is given that both have same Velocity so,

For the Second case, u = 50m/s

Therefore,

Second Case

→ s = ut + ½ × a × t²

→ s = 50 × 2 + ½ × 10 × (2)²

→ s = 100 + 5 × 4

→ s = 100 + 20

→ s = 120m

Therefore, The Height of body is 120m.

Answer 2

Answer:

QuEsTiOn

A body thrown vertically upwards from the top of a building in 5s if the body is thrown vertically downwards with the same velocity it will take only 2s to reach the foot of the building calculate the height of the building and the velocity with which it was thrown

To find

calculate the height of the building and the velocity with which it was thrown

Answer

Formula = v = u + at

➡️0 = u + -10 × 5

➡️= -u = -50.

➡️U = 50 m/s

So, the initial velocity is 50 m/s

2nd case

➡️s = ut + ½ × a × t²

➡️ s = 50 × 2+ ½ × 10 × 2²

➡️s = 100 +5× 4

➡️ s = 100+200 = 300

Height of body = 120 m

Hope it helps