Question

A train engineer started the train from a standstill and sped up to 5 meters per second, she then rounded a corner at a constant speed. She then sped the train up to 10 meters per second on the next straightaway. Next, the train chugged around another bend at 10 m/sec, and then its speed slowed to 5 meters per second after coming out of the bend. Finally, the train reached the station, and the engineer applied the brakes and brought the engine to a stop. How many times did the train accelerate? A) 2 B) 4 C) 5 D) 6

Answer 1

The train accelerated continuously, throughout the trip. Six phases of the trip are described in the question. (D)

Answer 2

Answer:

D) 6 times

Explanation:

acceleration is rate of change in velocity

So the train will accelerate either when its velocity will change its magnitude or the direction of train will change.

So here lets discuss the motion of train

1) Engineer started the train from a standstill and sped up to 5 meters per second,

Since speed is increasing so its accelerating

2) then rounded a corner at a constant speed.

Since direction of velocity is changing so its accelerating

3) then speed the train up to 10 meters per second on the next straightaway.

Speed is increasing so its accelerating

4) Next, the train chugged around another bend at 10 m/sec,

Since direction of velocity is changing so its accelerating

5) then its speed slowed to 5 meters per second after coming out of the bend.

Speed is decreasing so its accelerating

6) Finally, the train reached the station, and the engineer applied the brakes

Brakes are applied so its accelerating

So it must be accelerating 6 times