B. moving electric charges, hope this helps :)
Answer:
5 weeks and 5 days is required to empty the lake
Explanation:
Officials begin the remove water from a full man made lake
The lake can be emptied in 4 weeks
= -1/4
A river can fill the lake up in 15 weeks
= 1/15
Let t represent the number of weeks that is required to empty the lake
= -1/t
Therefore the number of weeks it takes to empty the lake can be calculated as follows
-1/t= -1/4 + 1/15
-1/t= -11/60
Cross multiply
-11×t= -1×60
-11t= -60
t = 60/11
t= 5 5/11
Hence it takes 5 weeks and 5 days to empty the lake
Answer:
The frequency of the phonograph record is 0.2 Hz
Explanation:
The frequency of an object moving in uniform circular motion is the number of completed cycles the object makes in a specified time period
The given parameters of the phonograph record are;
The radius of the record = 0.15 m
The number of times the phonograph record rotates, n = 18 times
The time it takes the phonograph record to rotate the 18 times, t = 90 seconds
The frequency of the phonograph record, f = (The number of times the phonograph record rotates) ÷ (The time it takes the phonograph record to rotate the 18 times)
∴ The frequency of the phonograph record, f = n/t = 18/(90 s) = 0.2 Hz
The frequency of the phonograph record = 0.2 Hz.
Answer:
34 m/s
Explanation:
m = Mass of glider with person = 680 kg
v = Velocity of glider with person = 34 m/s
= Mass of glider without person = 680-60 kg
= Gliders speed just after the skydiver lets go
= Mass of person = 60 kg
= Velcotiy of person = 34 m/s
As the linear momentum of the system is conserved
The gliders speed just after the skydiver lets go is 34 m/s
Distance fallen = 1/2 ( V initial + V final ) *t
We know
a = -9.8 m/s2
t=120s
To find distance fallen, we need to find V final
Use the equation
V final = V initial + a*t
Substitute known values
V final = 0 + (-9.8)(120)
V final = -1176 m/s
Then plug known values to distance fallen equation
Distance fallen = 1/2 ( 0 + 1176 )(120)
= 1/2(1776)(120)
=106,560 m
This way plugging into distance equation is actually the long way. A faster way is to plug the values into
Distance fallen = V initial * t + 1/2(a*t)
We won't need to find V final using another equation.
But anyways, good luck!
