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.

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

also in Y direction

now we have

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.

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =