Answer:
73 db
Explanation:
A single air conditioner is equivalent to 70 dB frequency. An extra air conditioning unit would therefore double the sound frequency. It does not, however, double the decibels to 140 dB. Instead, it adds only 3 dB to the 70 dB, making the total decibels of two air conditioning units equal to 73 db
Hence the correct option is b that is 73 db
Answer:
She run for, t = 0.92 s
Explanation:
Given data,
The velocity of the runner, v = 10 km/h
The distance covered by the runner, d = 9.2 km
The relationship between the velocity, displacement and time is given by the formula,
t = d / v
Substituting the given values in the above equation,
t = 9.2 / 10
= 0.92 s
Hence, she ran for, t = 0.92 s
Answer:
F = 2.49 x 10⁻⁹ N
Explanation:
The electrostatic force between two charged bodies is given by Colomb's Law:

where,
F = Electrostatic Force = ?
k = colomb's constant = 9 x 10⁹ N.m²/C²
q₁ = charge on proton = 1.6 x 10⁻¹⁹ C
q₂ = second charge = 1.4 C
r = distace between charges = 0.9 m
Therefore,

<u>F = 2.49 x 10⁻⁹ N</u>
Answer:
50 W
Explanation:
Case 1
Power = V * I
100 = 220 * I
I =
A
Case 2
P = V * I
P = 110 * 
P = 50 W
I think the answer is 50 W
Hope it helps
Answer:
D) momentum of cannon + momentum of projectile= 0
Explanation:
The law of conservation of momentum states that the total momentum of an isolated system is constant.
In this case, the system cannon+projectile can be considered as isolated, because no external forces act on it (in fact, the surface is frictionless, so there is no friction acting on the cannon). Therefore, the total momentum of the two objects (cannon+projectile) must be equal before and after the firing:

But the initial momentum is zero, because at the beginning both the cannon and the projectile are at rest:

So the final momentum, which is sum of the momentum of the cannon and of the projectile, must also be zero:
