Answer:
Explanation:
frequency of whistle = 1.85 x 10² = 185 Hz
frequency of beat heard = 8 beat /s . No of beat produced is equal to difference of frequencies of two sound source . Here difference is created due to Doppler effect . One of the train is moving so it will have apparent frequency which is different one from its original frequency .
When the moving train is approaching the observer , its frequency will be higher . As beat is heard at the rate of 8 beats / s , apparent frequency of approaching train will be 185 + 8 = 193 Hz .
Applying Doppler's formula of apparent frequency ,
193 = 185 x V / ( V - v ) , where V is velocity of sound and v is velocity of train .
193 V - 193 v = 185 V
193 v = 8 V
v = 8 x V / 193
= 8 x 343 / 193
= 14.21 m /s
Second possibility is that apparent velocity is less ie 185 - 8 = 177 Hz
In that case moving train will be moving away from observer . If its velocity be v
177 = 185 x V / ( V + v )
177 V + 177 v = 185 V
v = 8 x 343 / 177
= 15.50 m /s .
Answer:
The correct option is a
Explanation:
This question seeks to test a general rule in physics (on charges) which states that <u>like charges repel but unlike charges attract</u>. This means that, a negatively charged substance will repel or not attract another negatively charged material and the same applies to a positively charged substance also. However, a <u>negatively charged substance will attract a positively charged material and vice versa,</u> hence only a negatively charged rod will attract a positively charged hanging ball.
In order to find which rational number is between 0 and 1, let's convert them into their decimal form:

Looking at the numbers in their decimal form, we can see that the number between 0 and 1 is one-fourth, therefore the correct option is the second one.