We know that frequency is an inverse value of time
this implies that time is the inverse value of frequency
.
Now since <em>f</em> is <em>40kHz</em><em>,</em><em> </em>we can calculate period or duration for that matter time.

Hope this helps.
r3t40
A funnel shaped cloud is called a funnel cloud.
If it touches the ground it is called a tornado.
The uncertainty of the measurement is 0.001 gm.
The uncertainty in the measurement of a physical quantity is given as how precisely we can measure that, in this case as we can see that the mass of the sodium chloride is precisely given as 29.732 gm, this means the electronic scale is precise to 0.001 gm and round of the values after that which means there is a uncertainty of 0.001 gm.
. Methylated spirits have ethanol as a base but may include methyl alcohol (methanol) as part of the denaturing process.
First thing plot a right angle with angle of elevation of 35degrees as shown in figure then use SOHCAHTOA.
Ay/Helicopter = sin 35
Ay = 86 sin 35 = 36.8237
Ax/Helicopter = cos 35
Ax = 86 cos 35 = 77.7175
Note: I ignore the negative signs coz they signify direction