Question

An object thrown vertically upwards reaches a height of 320 m. What was its initial velocity? (Assume g = 10 m/s2) *​

Answer 1

Answer:

the answer is

$80 {ms}^{ - 1}$

Explanation:

an object thrown vertically upwards reaches height of 320m

now at the highest point the final velocity (v) will be 0 because the object will come to rest at highest point and after that it will start free fall from that point.

now, initial velocity (u)

h is the height covered which is given as 120m.

Now assuming the upward side as positive and downward sign as negative we get,

h = 320m

v = 0

u = ?

a(acceleration due to gravity) = - g

( '-' sign is because gravity always acts downwards and we jave assumed the downward sign as negative)

now we know the formula that,

${v}^{2} = {u}^{2} + 2as$

here s is the height 'h'

and a = - g

value of

$g = 10 {ms}^{ - 2}$

${v}^{2} = {u}^{2} - 2gh \\ 0 = {u}^{2} - 2 \times 10 \times 320 \\ 0 = {u}^{2} - 6400 \\ {u}^{2} = 6400 \\ u = \sqrt{6400} \\ u = 80 {ms}^{ - 1}$