It's simple.
We know force is the rate of change in momentum.
So F=(mv-mu)/t or F=m(v-u)/t
=1200*(25-10)/5=3600N
Franklin had been waiting for an opportunity like this. He wanted to demonstrate the electrical nature of lightning, and to do so, he needed a thunderstorm.
He had his materials at the ready: a simple kite made with a large silk handkerchief, a hemp string, and a silk string. He also had a house key, a Leyden jar (a device that could store an electrical charge for later use), and a sharp length of wire. His son William assisted him.
Franklin had originally planned to conduct the experiment atop a Philadelphia church spire, according to his contemporary, British scientist Joseph Priestley (who, incidentally, is credited with discovering oxygen), but he changed his plans when he realized he could achieve the same goal by using a kite.
The net force on the sled is 300 N
Explanation:
First of all, we start by finding the acceleration of the bobsled, by using the suvat equation:

where:
v = 6.0 m/s is the final velocity of the sled
u = 0 is the initial velocity
a is the acceleration
s = 4.5 m is the displacement of the sled
Solving for a, we find

Now we can find the net force on the sled by using Newton's second law:
F = ma
where
F is the net force
m = 75 kg is the mass of the sled
is the acceleration
Solving the equation, we find the net force:

Learn more about acceleration and Newton laws here:
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This is the process of changing the shape of the eye lens to focus on near or distant objects.
Given that,
Output power = 87 W
Decibel reading = 120 dB
We need to calculate the intensity of sound
Using formula of intensity of sound

Put the value into the formula





We need to calculate the distance
Using relation of power out[ut and intensity

Put the value into the formula



Hence, The distance is 2.63 m