Question

You are conducting an experiment inside a train car that may move along level rail tracks. A load is hung from the ceiling on a string. The load is not swinging, and the string is observed to make a constant angle of 45∘ with the horizontal. No forces other than tension and gravity are acting on the load. Which of the following statements are correct?Statements include: 1. The train is an inertial frame of reference. 2. The train is not an inertial frame of reference. 3. The train may be at rest. 4. The train may be moving at a constant speed in a straight line. 5.The train may be moving at a constant speed in a circle. 6. The train must be speeding up. 7. The train must be slowing down. 8. The train must be accelerating.

Answer 1

Answer:

correct answers will be

2. The train is not an inertial frame of reference.

5.The train may be moving at a constant speed in a circle.

8. The train must be accelerating.

Explanation:

As we know that string makes an angle with the horizontal

so we can write the force equation for the given ball

$F_x = Tcos\theta$

$ma = Tcos45$

also in Y direction

$mg = Tsin45$

now we have

$\frac{ma}{mg} = cot 45$

$a = g cot45$

now we can conclude that train is accelerating with acceleration same as gravity

now correct answers will be

2. The train is not an inertial frame of reference.

5.The train may be moving at a constant speed in a circle.

8. The train must be accelerating.