Amotor car of mass 1200kg is moving along a straight line with uniform velocity of 90km/hr. its velocity is slowed down to 18km/hr in 4s by an unbalanced external force. calculate the acceleration and change in momentum. also calculate the external force acting on it.

Initial velocity (u) = 90km/hr = 90/3.6 m/s = 25m/s
final velocity (v) = 18km/hr = 18/3.6 m/s = 5m/s
acceleration = (v-u)/t = (5-25)/4 = -5 m/s2
change in momentum = m(v-u) = 1200(5-25) = -24000 kg•m/s
F = ma = 1200 x -5 = -6000 N

Given :

An ant is crawling along a yardstick that is pointed with the 0-inch mark to the east and the 36-inch mark to the west.

It starts at the 14-inch mark, crawls to the 20-inch mark, then moves to the 16-inch mark.

To Find :

The total distance the ant traveled.

Solution :

Total distance travelled by ant = (distance between 14 and 20 inch mark) +

                                                      (distance between 20 and 16 inch mark)

Total distance = (20-14 ) + ( 20-16) = 6 + 4 = 10 inch.

Therefore, total distance the ant traveled is 10 inch.

Hence, this is the required solution.