show that if there is no external force, The velocity decays exponentially from velocity to zero as time tends to infinity​

An insurance company wants to know if the average speed at which men drive cars is higher than that of women drivers. the company took a random sample of 27 cars driven by men on a highway and found the mean speed to be 72 miles per hour with a standard deviation of 2.2 miles per hour. another sample of 18 cars driven by women on the same highway gave a mean speed of 68 miles per hour with a standard deviation of 2.5 miles per hour. assume that the speeds at which all men and all women drive cars on this highway are both approximately normally distributed with unknown and unequal population standard deviations.

Due sun 06/09/2019 11: 59 pm skip navigation questions correct q 1 [1/1] correct q 2 [1/1] correct q 3 [1/1] untried q 4 (0/1) untried q 5 (0/1) untried q 6 (0/1) untried q 7 (0/1) untried q 8 (0/1) untried q 9 (0/1) untried q 10 (0/1) grade: 3/10 print version start of questions two cyclists, 42 miles apart, start riding toward each other at the same time. one cycles 2 times as fast as the other. if they meet 2 hours later, what is the speed (in mi/h) of the faster cyclist?

Would it be correct to say the doppler effect is the apparent change in the speed of a wave due to the motion of the source? be sure to fully explain your position using at least 3 complete content related sentences.