Question

A stone is thrown vertically upwards with an initial velocity of 20m/s .How high will the stone rise above ground level of the cliff?

Answer 1

Initial velocity of the stone (u) = 20 m/s

Maximum height reached by the stone (h) = ? m

Acceleration due to gravity , g = - 10 m/s²

• Since the stone thrown against the gravity

Final velocity of the stone (v) = 0 m/s

• As the stone goes to rest in extreme position

Apply 3rd equation of motion ,

⇒ v² - u² = 2gh

⇒ (0)² - (20)² = 2(-10)h

⇒ 0 - 400 = - 20h

⇒ -400 = -20h

⇒ 20h = 400

⇒ h = 40/2

⇒ h = 20 m  $\pink{\bigstar}$

Maximum height reached by the stone is 20 m

Answer 2

Question:-

A stone is thrown vertically upwards with an initial velocity of 20m/s .How high will the stone rise above ground level of the cliff ?

Formulas:-

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

Given:-

• Stone is thrown with a vertical direction with velocity (u) = 20m/s

• The acceleration due to gravity of stone is, v = 0

• Then what is the height maximum height reached by stone.

Solution:-

v = 0 ; u = 20m/s ; g = -10m/s² ; h = ?

️ ➭ v² - u² = 2gs

️ ➭ 0² - 20² = 2(-10)(s)

️ ➭ -400 = -20s

️ ➭ s = 400/20

️ ➭ s = 20m

∴ The maximum height reached by stone is 20m

★ Hence Verified