Question

An object is thrown vertically upward to a height of 12m . Calculate its velocity with which it was thrown upwards. Time taken by the object to reach a height of 12m​

Answer 1

Answer:-

→ The object was thrown upwards with a velocity of 15.34 m/s .

→ Required time taken is 1.56 s .

Explanation:-

Max height reached = 12 m

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Since, the object is thrown vertically upwards. So in this case :-

• Velocity of the object at the highest point will be zero. [ v = 0 ]

• Acceleration due to gravity will be -9.8 m/s² as the object is going against the gravity.

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By using 3rd equation of motion, we get :-

⇒ v² = u² + 2gh

⇒ 0 = u² + 2(-9.8)12

⇒ 0 = u² - 235.2

⇒ u² = 235.2

⇒ u = √235.2

⇒ u = 15.34 m/s

Now, by using the 1st equation of motion :-

⇒ v = u + gt

⇒ 0 = 15.34 + (-9.8)t

⇒ -15.34 = -9.8t

⇒ t = -15.34/-9.8

⇒ t = 1.56 s

Answer 2

Answer:

Given :-

• An object is thrown vertically upward to a height of 12 m.

To Find :-

• Calculate it's velocity with which it was thrown upwards.
• Time taken by the object to reach a height of 12 m.

Formula Used :-

➲ v² = u² + 2gh

➲ v² = u + gt

where,

• v = Final velocity
• u = Initial velocity
• g = Acceleration due to gravity
• h = Height

Solution :-

⓵ To find velocity with which it was thrown upwards :

Given :

• Final velocity (v) = 0 m/s
• Acceleration due to gravity (g) = - 9.8 m/s²
• Height (h) = 12 m

According to the question by using the formula we get,

↦ (0)² = u² + 2 × (- 9.8) × 12

↦ 0 = u² + 24 × (- 9.8)

↦ 0 = u² - 235.2

↦ √235.2 = u

↦ 15.34 = u

➠ u = 15.34 m/s

∴ The velocity with which it was thrown upwards is 15.34 m/s.

⓶ Time taken by the object to reach a height of 12 m :

Given :

• Final velocity = 0 m/s
• Initial velocity = 15.34 m/s
• Acceleration due to gravity = - 9.8 m/s²

According to the question by using the formula we get,

↦ 0 = 15.34 + (- 9.8) × t

↦ 0 = 15.34 - 9.8 × t

↦ 0 = 15.34 - 9.8t

↦ - 15.34 = - 9.8t

↦ - 15.34/9.8 = t

↦ - 1.56 = t

➦ t = 1.56 seconds

∴ The time taken by the object to reach a height of 12 m is 1.56 seconds.