Question

A bullet shot straight up returns to its starting point in 10 sec. the initial speed was?
(A) 9.8 m/s
(B) 24.5 m/s
(C) 49 m/s
(D) 98m/s​

Answer 1

Answer :

The initial speed of the bullet when it was shot straight up returns to its starting point in 10 sec is 49 m/s.

Explanation :

Given parameters:

Time taken =10 sec

To Be Calculated:

The initial speed of the bullet (u)

Solution:

Since the ball returns to its initial position, then the displacement will be zero,

Initial velocity is the velocity with which it started its motion. It is denoted by u.

Displacement is the shortest distance between the initial and final point.

So, displacement (s) = 0

There are three equations of motion :

$v = u +at\\s = ut +\frac{1}{2} at^{2} \\v^{2} -u^{2} =2as$

Since we know the displacement, time, and acceleration, we calculate the initial velocity by employing the second equation of motion.

So, By using the second equation of motion, we have

$s = ut + \frac{1}{2} at^{2}$

By putting all the values in the above equation, we have :

$0 = u*10 + \frac{1}{2} *9.8(10)^{2}\\\\10u = 490\\\\ u = 49 m/s$

Thus, the initial velocity of the ball is 49 m/s

To read more about velocity, we have

https://brainly.in/question/47776531

https://brainly.in/question/32589442

#SPJ1

Answer 2

Answer:

as we know that equations of motion s

s=distance cover by object

Vi=Initial velocity

Vf=Final velocity

t=time