You need to know the formula:
25 = 1/2 * g * t^2
t = √(50/g) = 2.258 s, where I use g = 9.8 m/s^2
Answer:
Explanation:
Radio waves travel at the speed of light
= Speed of light = 
= Distance between two radios = 46 km
= Speed of sound in air = 348 m/s
= Distance sound travels across the newsroom = 2.1 m
Time taken by the radio signal to reach the required location is
Time taken by sound to reach the required location is
The time difference is
The difference in time that the message is received is .
Power = (work done) / (time to do the work)
Work done = (force) x (distance)
Force = (weight of the crate) = (mass of the crate) x (gravity)
Crate weight = (100 kg) x (9.8 m/s²)
Force = 980 Newtons
Work done = (980 N) x (2 m) = 1,960 Joules
Power = (1,960 Joules) / (4 seconds)
<em>Power = 490 Joules per second</em>
(Whoever wrote the question used 10 m/s² for gravity instead of 9.8 m/s², so his answer came out to be 500 W. That's <em>choice-B</em> .)
<em>Power = 490 watts</em>
B) They want the electric current to be carefully controlled so they use a metalloid as a semiconductor.
<span>D)bismuth (Bi), antimony (Sb), nitrogen (N) because of the number of free electrons in the lattice.
</span><span>C.) selenium (Se), germanium (Ge), potassium (K)
</span>again because of the free electrons in the lattice.
Hope this helps.
