Answer: 0.25 seconds.
Explanation:
The yo-yo does 240 revolutions in one minute, and we know that one minute has 60 seconds, then the revolutions per second can be calculated as:
240 rev/60s = 4 rev/s, this will be the frequency of the yo-yo
The frequency is actually written as: f = 4 Hz = 4 s^-1
We want to find the period of this yo-yo.
The period is the duration of one cycle, and we have the relation:
f = 1/T
Where f is the frequency and T is the period, then:
T = 1/f
And we know the value of f, it is f = 4 s^-1
Then the period will be:
T = 1/(4 s^-1) = (1/4) s
Then the period of the yo-yo is 1/4 seconds = 0.25 seconds.
Answer:
B) 1.5 m/s
Explanation:
The apparent frequency will be enhanced due to Doppler effect
If f be the apparent frequency , F be the real frequency , V be the velocity of sound and v be the velocity of approaching submarine then f is given by
f = F \frac{V+v}{V-v}\\
\frac{f}{F} =\frac{V+v}{V-v}\\
\frac{f}{F}-1 =\frac{V+v}{V-v}-1\\
\Delta f = \frac{2vf}{V-v}\\
200=\frac{2\times v\times 100\times 1000}{1482-v}\\
v=1.48 m/s
Answer:
The ballon would be inflated. The reason is that the sodium bicarbonate in baking soda reacts with acetic acid in vinegar to produce gas.
Explanation:
The main component of baking soda is sodium bicarbonate, 
.
Vinegar is mostly a solution of acetic acid 
in water.
Acids such as acetic acid react with carbonate salts. One of the products of such reactions is carbon dioxide 
, a gas.
In this question, when the acetic acid in vinegar reacts with sodium bicarbonate in the baking soda, the following reaction would occur:
.
The produced would then inflate the ballon placed on the opening of the bottle.
