While playing basketball in pe class, 67 kg johan lost his balance after making a lay-up at 5.4 m/s and collided with the padded wall behind the basket and came to rest in 0.24 seconds. what force acted on his body?

a. -1300
b. -1500
c. -1700
d. -1900

-1500

Explanation:

According to newtons second law which states that the change in momentum of a body is directly proportional to the applied force and acts in the direction of the force. Mathematically,

Force = mass(m)×acceleration(a)

Where acceleration = change in velocity/time(t)

Acceleration = final velocity(v)-initial velocity (u)

Force= m(v-u)/t

Given Mass = 67kg, initial velocity = 5.4m/s, final velocity= 0m/s, time = 0.24seconds.

Substituting the values in the formula we have;

Force = 67(0-5.4)/0.24

= 67(-5.4)/0.24

Force = -361.8/0.24

Force = -1507.5

Therefore a force of -1500 is acting on the body

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

at right angles to each other