## Physics Boat Problems

**Introduction to physics boat problems:**

In water the direction along the stream is called downstream. And, the direction against the stream is called upstream.

If the speed of a boat in still water is u km/hr and the speed of the stream is v km/hr, then:

Speed downstream = (u+v) km/hr

Speed upstream = (u-v) km/hr

Having problem with Units of Angular Momentum keep reading my upcoming posts, i will try to help you.

**Problems on physics boat problems:**

Ex:1 A man can row upstream at 7 km/hr and downstream at 10km/hr. Find man's rate in still water and the rate of the current.

Sol: - Rate in still water = ½(10+7) km/hr = 8.5 km/hr.

Rate of current = ½ (10-7) km/hr = 1.5 km/hr. (Answer)

Ex:2- A man takes 3 hours 45 minutes to row a boat 15 km downstream of a river and 2 hours 30 minutes to cover a distance of 5 km upstream. Find the speed of the river current in km/hr.

sol: - Rate downstream = (15km/3 hours 45 minutes) = 15 * 4/15 km/hr = 4 km/hr.

Rate upstream = (5 km/2hours 30 minutes) = 5*2/5 km/hr = 2 km/hr.

Therefore, speed of current = ½(4-2) km/hr = 1 km/hr. (Answer)

Ex:2 There is a road beside a river. Two friends started from a place A, moved to a temple situated at another place B and then returned to A again. One of them moves on a cycle at a speed of 12 km/hr, while other sails an a boat at a speed of 10 km/hr. If the river flows at the speed of 4 km/hr, which of the two friends will return to place A first?

Sol: - Clearly, the cyclist moves both ways at the speed of 12 km/hr.

So, average speed of the cyclist = 12 km/hr.

The boat sailor moves downstream @ (10+4) i.e., 14 km/hr and upstream@ (10-4) i.e., 6 km/hr.

So, average speed of the boat sailor = (2*14*6)/ (14+6) km/hr

= 42/5 km/hr = 8.4 km/hr

Since the average speed of the cyclist is greater, he will return to A first. (Answer)

Looking out for more help on fahrenheit to celsius equation in physics by visiting listed websites.

**Practice problems on physics boat problems:**

Problem: - In one hour, a boat goes 11 km along the stream and 5 km against the stream. The speed of the boat in still water (in km/hr) is. (Answer: 8 km/hr)

Problem: - A boat running downstream covers a distance of 16 km in 2 hours while for covering the same distance upstream, it takes 4 hours. What is the speed of the boat in still water? (Answer:6 km/hr)

Problem: - A boat can travel with a speed of 13 km/hr in still water. If the speed of the stream is 4 km/hr, find the time taken by the boat to go 68 km downstream. (Answer: 4 hours).

Problem: - A boat covers a certain distance downstream in 1 hour, while it comes back in 1 and ½ hours. If the speed of the stream be 3 km/hr, what is the speed of the boat in still water? (Answer: 15 km/hr)

Problem: - A boat takes 90 minutes less to travel 36 miles downstream than to travel the same distance upstream. If the speed of the boat in still water is 10 mph, the speed of the stream is? (Answer: 2 mph)