The position of a baseball relative to home plate changes from 20, 7, −1 m to 25, 9, −5 m in 0.1 s. as a vector, write the average velocity of the baseball during this time interval. (express your answer in vector form.)

Explanation:

x = < 20, 7, -1 > m

y = < 25, 9, - 5> m

t = 0.1 s

Displacement between x and y is given by

z = y - x

z = < 25 - 20, 9 - 7, - 5 + 1>

z = < 5, 2, - 4 >

Magnitude of displacement is given by

= 6.71 m

Average velocity = total displacement / total time = 6.71 / 0.1 = 67.1 m/s

the answer would be c

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s