Question

A ball thrown vertically upward reaches the ground back in 5 seconds. Calculate the velocity with which it strikes the ground​

Answer 1

Given:-

• Acceleration due to gravity ,g = 10m/s²
• Time taken ,t = 5s
• Final velocity ,v = 0m/s (as it strike the ground)

To Find:-

• Initial velocity ,u

Solution:-

According to the Question

we have to calculate the velocity of ball which it strikes the ground .

Since the ball reached maximum height & returned to their initial position . Therefore ,the time taken by ball to come at the ground .

$:\implies$ t = 5/2 = 2.5 s

Using 1st equation of motion

• v = u +at

where,

• v is the final velocity
• a is the acceleration
• u is the initial velocity
• t is the time taken

Substitute the value we get

$:\implies$ 0 = u + (-10) × 2.5

$:\implies$ 0 = u -10×2.5

$:\implies$ -u = -10×2.5

$:\implies$ u = 25m/s

• Hence, the velocity of ball which it strikes the ground is 25m/s

Answer 2

Given :-

A  ball thrown vertically upward reaches the ground back in 5 seconds.

To Find :-

Velocity

Solution :-

Since the ball is thrown vertically upwards

Time = 5/2 sec

Now

v = u + at

0 = u + -10 × 5/2

0 - u = -10 × 5/2

-u = -5 × 5

-u = -25

u = 25

Hence,

Velocity is 25 m/s

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