Train a leaves new york for boston at 3 pm and travels at the constant speed of 100 mph. an hour later, it passes train b, which is making the trip from boston to new york at a constant speed. if train b left boston at 3: 50 pm and if the combined travel time of the two trains is 2 hours, what time did train b arrive in new york? (1) train b arrived in new york before train a arrived in boston.(2) the distance between new york and boston is greater than 140 miles.

Explanation:

Let the distance between New York and Boston be s.

Train A leaves New York for Boston at 3 PM and travels at the constant speed of 100 mph.

Time taken by train A

An hour later, it passes Train B, which is making the trip from Boston to New York at a constant speed. If Train B left Boston at 3:50 PM

At 4:00 PM combined distance by them is s.

Let the speed of train B be v.

We have

                     100 x 1 + v x 0.167 = s

Time taken by train B

The combined travel time of the two trains is 2 hours

That is

Given that the distance between New York and Boston is greater than 140 miles.

So the distance is 150 miles.

Time taken by train B

Time of arrival of train B = 3:50 PM + 0.5 hours = 4:20 PM

Time of arrival of train B is 4:20 PM

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.