A car with an initial speed of 31.4 km/h accelerates at a uniform rate of 1.2 m/s2 for 1.3 s. What is the displacement of the car during this time? Select the most appropriate choice

21.5 m

Explanation:

A car has an initial speed of 31.4 km/hr

Convert to m/s

= 31.4 × 1000/3600

= 31,400/3600

= 8.722 m/s

Acceleration = 1.2 m/s^2

Time= 1.3 seconds.

Therefore the displacement can be calculated as follows

S= 8.722 × 1.3 + 1/2 × 1.2 × 1.3^2

= 11.34 + 1/2 × 20.28

= 11.34 + 10.14

= 21.5 m

double the distance = divide strength by 4

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