Question

A stone is thrown upwards with a velocity of 72km/hr. If the air is neglected. find the minimum height travelled by it

Answer 1

Correct question :

A stone is thrown upwards with a velocity of 72km/hr. If the air is neglected. Find the maximum height travelled by it.

Answer:

Maximum height reached by stone

= 20 m

Step by step explanations :

Given that,

A stone is thrown upwards with a velocity of 72km/h

Here,

Initial velocity of the stone = 72 km/h

by changing it into m/s

72 km/h

= 72 × 1000m/60 × 60s

= 72 × 5/18

= 4 × 5

= 20 m/s

let the maximum height reached by the stone be h

at the maximum height(h) final velocity will be 0 m/s

Now we have,

Initial velocity(u) = 20 m/s

final velocity(v) = 0 m/s

maximum height(h) = h

gravitational acceleration(g) = -10 m/s²

By the gravitational equation of motion,

v² = u² + 2gh

putting the values,

0² = 20² + 2 × (-10) h

-20h = -400

h = -400/-20

h = 20 m

so,

Maximum height reached by stone

= 20 meter

Answer 2

Answer:

Maximum height reached by stone

= 20 m

Step by step explanations:

Given

initial velocity of stone = 72 km/h

= 72 × 5/18

= 20 m/s

maximum height and minimum height will be the same

because initial velocity is given

let the maximum height reached by stone be h

so,

final velocity(v) = 0 m/s

Initial velocity(u) = 20 m/s

gravitational acceleration(g) = -10 m/s²

v² = u² + 2gh

putting the values,

0² = 20² + 2 × (-10) h

-20h = -400

h = -400/-20

h = 20 m

so,

Minimum height reached by stone

= 20 m