A crew team rows a boat at a rate of 20km/h in still water.Beginning at time =0minutes, the team rows for 30minutes up a river(against the current).The speed of the current is 1.5 km/h.How long will it take the crew team to row down the river(with the current)to return to thestarting point?

--

20. If it were possible for a rocket to travel at the speed of light (3.0 x 108 m/s), about how long would it take to reach this speed from rest? Assume the rocket accelerates at a rate of 750 m/s2

Speed of boat = 20 km/h & speed of current = 1.5 km/h....

Since the boat traveled (30 minutes) against direction of current therefore effective speed of boat was

20-1.5 =18.5 km/h

distance traveled in 30 minutes ( 0.5 hrs) against the current =18.5 x 0.5 = 9.25 km

NOw crew has to return 9.25 km along the direction of current hence speed will be 20+1.5 = 21.5 km/h

therefore time required to reach starting point = distance/speed = 9.25/21.5 = 0.4302 hrs or 25.8 minutes

20. v = u+at

3x 10^8 = 0+ 750 * t

hence, t = 3x10^8/750 =400000 sec =111.111 hrs

Dear student: Please find the solution enclosed
here with .. In case of any doubt please feel free to askā¦ If you are having some other
problem please feel free to contact me for quick & quality services..Use my promo code: Saroj N or link: studypool.com?aid=Saroj N, and get $10 Free.