Answer:
a) 16.46 seconds.
b) 13.46 seconds
c) 2.67 m/s²
Explanation:
Acceleration = a = 1.35 m/s²
Final velocity = v = 80 km/h = 
Initial velocity = u = 0
Equation of motion

Time taken to accelerate to top speed is 16.46 seconds.
Acceleration = a = -1.65 m/s²
Initial velocity = u = 80 km/h= 
Final velocity = v = 0

Time taken to stop the train from top speed is 13.46 seconds
Initial velocity = u = 80 km/h= 
Time taken = t = 8.3 s
Final velocity = v = 0

Emergency deceleration is 2.67 m/s²
Answer:
D.
Explanation:
This is the essence of “correlation does not imply causation”. When there is a common cause between two variables, then they will be correlated. This is part of the reasoning behind the less-known phrase, “ There is no correlation without causation ”.
Answer:
Step down transformers are used in power adaptors and rectifiers to efficiently decrease the voltage. They are also used in electronic SMPS.
Explanation:
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Answer:
The first overtone frequency is 100 Hz.
Solution:
According to the question:
Length of pipe, l = 1.75 m
Speed of sound in air, v_{sa} = 350 m/s
Frequency of first overtone,
is given by:


Since, the frequency, as clear from the formula depends only on the speed
and the length. It is independent of the air temperature.
Thus there will be no effect of air temperature on the frequency.