Question

A tennis ball is thrown up and reaches
acceleration due to gravity (g)=10m/s
which it strikes the ground respectively is
own up and reaches a certain height and comes down in 8s. If value of
Lo gravity (g)=10m/s2. then height reached by tennis ball and velocity with
-
and
(1) 640 m, 160 m/s
(2)
320 m, 120 m/s
(3)
160 m, 80 m/s
(4)
80 m, 40 m/s.
cool temperature of the mixture.​

Answer 1

Answer:

(4) 80 m ,40 m/s

Explanation:

1) We have,

Time of flight, T=8s .

So, Time taken by tennis ball to to move from ground to top, = 8/2=4 s

At top, final velocity v = 0

Then, using Newton's equation of motion, (in y-direction)

Acceleration, a = -10 m/s^2

$v=u+at\\ \\=>0=u-10*4\\ \\=>u=40 m/s$

Hence, Initial velocity of ball is 40 m/s.

2) Again , using Newton's equation of motion.( in y-direction)

$u_y=40 m/s\\ \\t=4s\\ \\a=-10m/s^2$

$S=ut+\frac{at^2}{2}\\ \\=>S=40*4-\frac{10}{2}*4^2\\ \\ =160-80 = 80 m$

Hence, Height reached by tennis ball is 80 m.

Answer 2

SOLUTION.

HEY BUDDY...

As you get your solution so I provide you a different way to solve this question....

When we solve these type of question then we assume air resistance to be absent so that these question provide ideal conditions which is not possible....

Using these ideal condition...

• Time of flight = 8 sec

• When ball hits the ground the magnitude of velocity is same as the initial velocity but opposite in direction because of the ideal condition loss of energy is zero....

APPLY FIRST EQ OF MOTION....

V = U + gt

(-V = U)...... Discussed above

V = -V + gt

2V = gt

2V = 10(8)

2V = 80

V = 40m/sec

Initial velocity = 40m/sec

Acceleration due to gravity = g

v² = u² - 2gh

At max height velocity is zero...

0 = (40)² - 2(10)h

1600 = 20h

HEIGHT = 80m

#answerwithquality

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