Question

You and your brother both leave your house at the same instant and drive in separate cars along a straight highway to a nearby lake. After 10 min, you are both 3.0 km from your house. You are now driving at 100 km/h , and you continue at this constant speed; your brother is going faster than this. After another 20 min , your brother arrives at the lake, but you are still 7.0 km away.How far is it from your house to the lake? Express your answer with the appropriate units.What is your brother's average speed for the trip? Your brother beats you to the lake by what time interval?

Answer 1

The total time taken by the brother to reach the lake is, t=10 min + 20 min 605 =30 min = 1800 s The distance covered by the brother in 20 min is, d20ein = vt = (100 km hr) ( 9 21 km - (20 min) Photo = 33,333.36 m The distance from house to lake is, d = 3000 m +33,333.36 m + 7000 m = 43,333.36 m Hence, the distance from house to lake is 43,333.36 m. The average speed travelled by the brother during in this trip is, Yang -- 43,333.36 m 1800 s = 24.07 m/s Therefore, the average speed of the brother is 24.07 m/s. The time taken by the brother to beat you is. 7 km 100 km/hr =0.07 hr =(0.07 hr) 3600 = 252 s Hence, the time taken by the brother to beat you is 252 s.