Answer:
r₂=0.1 m
Explanation:
Given that
r₁= 10 m , β₁ = 20 dB
At r₂ ,β₂= 60 dB
As we know that intensity level of sound given as
10² x 10⁻¹² = I₁
I₁=10⁻¹⁰ W/m²
10⁶ x 10⁻¹² = I₂
I₂ = 10⁻⁶ W/m²
I₁=10⁻¹⁰ W/m²
P = I A
P=Power ,I =Intensity ,A=Area
r₂=0.1 m
Answer:
1.53 m/s
Explanation:
Given:
Mass of the car (M) = 1300 kg
Mass of the coal (m) = 400 kg
Initial velocity of the car (U) = 2 m/s
Initial velocity of the coal (u) = 0 m/s (Since it is dropped)
When the coal is dropped into the car, then they move with same final velocity.
Let the final velocity be 'v' m/s.
For a closed system, the law of conservation of momentum holds true.
So, initial momentum is equal to final momentum of the car-coal system.
Initial momentum of the car =
Initial momentum of the coal =
Total initial momentum is the sum of the above two momentums.
So, total initial momentum = 2600 + 0 = 2600 Ns
Now, final momentum is given as the product of combined mass and final velocity. So,
Final momentum of the system =
Now, from law of conservation of momentum,
Initial momentum = Final momentum
Therefore, the final velocity of either of the two masses is same is equal to 1.53 m/s.