A man goes from his house to office with a speed of 57km/hr and returns to the house with a speed of 83km/hr in his car. Calculate the average speed of the car.

70 km/h

Explanation:

The average speed is given by combining the two speeds and dividing them by two

Given

Speed to office as 57 km/h

Speed to house as 83 km/h

The differences in speeds may be due to the terrain of the land

Total speed is 57+83=140 km/h

Average speed is 140/2=70 km/h

Therefore, on average, the car went on a journey at the spees of 70 km/h

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