A ball thrown vertically upward takes four seconds to rise from the bottom of it

Question

A ball thrown vertically upward takes four seconds to rise from the bottom of its path to its highest point. At what time is its instantaneous speed equal to the magnitude of its average velocity for the entire upward motion from bottom to top?

a. Never

b. Always

c. At the start, that is, at the bottom.

d. At the top of its path.

e. At two seconds into its motion.

f. At some time before two seconds into its motion.

g. At some time after two seconds into its motion.

Two identical balls are thrown from the top of a cliff. One ball, ball A, is thrown straight up with speed v. The other, ball B, is thrown straight down with the same speed, v. Which of the statements below is correct?

a. Ball A always has a higher speed than ball B.

b. Ball A always has the same velocity as ball B.

c. Ball A always has the same speed as ball B.

d. Ball A always has a higher acceleration than ball B.

e. Ball A always has a smaller acceleration than ball B.

f. Ball A always has the same acceleration as ball B.

Explanation / Answer

here,

let the initial speed of the ball be u

at maximum height , v = 0

v = u - g * t

0 = u - 9.8 * 4

u = 39.2 m/s

average speed , v = (u + 0) /2

v = 19.6 m/s

let the time be t1

v= u - g * t1

19.6 = 39.2 - 9.8 * t1

t1 = 2 s

therefore , instantaneous speed equal to the magnitude of its average velocity for the entire upward motion from bottom to top when e. At two seconds into its motion
.............................

the correct statement are

c. Ball A always has the same speed as ball B.

f. Ball A always has the same acceleration as ball B. ( grvitational accelration is constant)

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