Question

Q1.From the top of a cliff 50m above sea level, a stone is thrown vertically upwards with a velocity of 15m/s. After how many seconds and with what velocity will it hit the sea

Answer 1

Step-by-step explanation:

SOLUTION

GIVEN

From the top of a cliff 50m above sea level, a stone is thrown vertically upwards with a velocity of 15m/s.

TO DETERMINE

After how many seconds and with what velocity will it hit the sea

EVALUATION

Here by the given -

• s = 50 m
• u = - 15 m/s
• a = 10 m/s²
• t = Time

We know that

v² = u² + 2as

⇒v² = 225 + 2 × 10 × 50

⇒v² = 225 + 1000

⇒v² = 1225

⇒ v = 35

The required velocity = 35 m/s

Again we have

v = u + at

⇒ 35 = - 15 + 10t

⇒ 10t = 50

⇒ t = 5

Hence the required time = 5 sec

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