Answer:
37.545 m/s
Explanation:
f' = Actual frequency of horn = 269 Hz
f = Observed frequency of horn = 290 Hz
v = Speed of sound in air = 343 m/s
= Speed of second train = 13.7 m/s
= Speed of first train
From Doppler effect we have

The speed of the first train is 37.545 m/s
Answer:
Explanation:
Given
Wheels are rotating with constant angular velocity let say 
Presence of constant angular velocity show that there is no angular acceleration thus there is no tangential acceleration.
But any particle on the rim will experience a constant acceleration towards center called centripetal acceleration.
(a) yes, there will be tangential velocity which is given by

where r=radial distance from center
(b)tangential acceleration
there would be no tangential acceleration as velocity is constant
(c)centripetal acceleration
Yes, there will be centripetal acceleration given by

The book that weighs less
Answer:
The right option is option E. None of the answer choices given are totally correct.
Explanation:
All insulators normally have an equal amount of positive and negative charges distributed on their surface.
The amber rod (an insulator) is called negative because after the coming together with fur (another insulator), the amber rod rubs off electrons from the fur onto itself and has an overall more negatively charged particles than positively charged particles on its surface.
The fur in turn becomes positive because it has more positive charges than negative on its surface.
So, the convention allows the now rubbed off amber rod to be called negative.
So, it is evident that none of the answer choices are totally correct, the right answer is more of a mix of some of the answer choices and more!
Hope this helps!!