Answer:
a. Object A
Explanation:
The mass of an object implies the quantity of matter in it, while the weight is the amount of gravitational force applied on an object.
The object A has a mass of 25 lbs, but object B on the earth has a weight, W, of 25 N.
So that,
For object A on the moon, mass = 25 lbs
For object B on the earth, W = 25 N,
W = m x g
25 = m x 10 (g = 10 m/
)
m = ![\frac{25}{10}](https://tex.z-dn.net/?f=%5Cfrac%7B25%7D%7B10%7D)
= 2.5 lbs
Mass of object B is 2.5 lbs.
Therefore, the mass of the object A is more than that of B.
Answer:
Explanation:
The two major defects of simple electric cells causes current supplied to be for short time. These defects are: polarization and local action.
a. Polarization: This is a defect caused by an accumulation of hydrogen bubbles at the positive electrode of the cell. It can be prevented by the use of vent, using a hydrogen absorbing material or the use of a depolarizer.
b. Local Action: This is the gradual wearing away of the electrode due to impurities in the zinc plate. It can be controlled by the amalgamation of the zinc plate before it is used.
Vacum flask has inner layer of glass and outer body of plastic.the glass has a reflective metal layer..when a hot drink is poured into the flask it prevents conduction.tight lid stops the convection.when radiation tries to leave the hot drink the reflective layer of the glass reflects it back so no heat can escape.
Answer:
r₂ = 0.2 m
Explanation:
given,
distance = 20 m
sound of average whisper = 30 dB
distance moved closer = ?
new frequency = 80 dB
using formula
![\beta = 10 log(\dfrac{I_1}{I_0})](https://tex.z-dn.net/?f=%5Cbeta%20%3D%2010%20log%28%5Cdfrac%7BI_1%7D%7BI_0%7D%29)
I₀ = 10⁻¹² W/m²
now,
![30 = 10 log(\dfrac{I_1}{10^{-12}})](https://tex.z-dn.net/?f=30%20%3D%2010%20log%28%5Cdfrac%7BI_1%7D%7B10%5E%7B-12%7D%7D%29)
![\dfrac{I_1}{10^{-12}}= 10^3](https://tex.z-dn.net/?f=%5Cdfrac%7BI_1%7D%7B10%5E%7B-12%7D%7D%3D%2010%5E3)
![I_1= 10^{-8}\ W/m^2](https://tex.z-dn.net/?f=I_1%3D%2010%5E%7B-8%7D%5C%20W%2Fm%5E2)
to hear the whisper sound = 80 dB
![80 = 10 log(\dfrac{I_2}{10^{-12}})](https://tex.z-dn.net/?f=80%20%3D%2010%20log%28%5Cdfrac%7BI_2%7D%7B10%5E%7B-12%7D%7D%29)
![\dfrac{I_2}{10^{-12}}= 10^8](https://tex.z-dn.net/?f=%5Cdfrac%7BI_2%7D%7B10%5E%7B-12%7D%7D%3D%2010%5E8)
![I_2= 10^{-4}\ W/m^2](https://tex.z-dn.net/?f=I_2%3D%2010%5E%7B-4%7D%5C%20W%2Fm%5E2)
we know intensity of sound is inversely proportional to square of distances
![\dfrac{I_1}{I_2}=\dfrac{r_2^2}{r_1^2}](https://tex.z-dn.net/?f=%5Cdfrac%7BI_1%7D%7BI_2%7D%3D%5Cdfrac%7Br_2%5E2%7D%7Br_1%5E2%7D)
![\dfrac{10^{-8}}{10^{-4}}=\dfrac{r_2^2}{20^2}](https://tex.z-dn.net/?f=%5Cdfrac%7B10%5E%7B-8%7D%7D%7B10%5E%7B-4%7D%7D%3D%5Cdfrac%7Br_2%5E2%7D%7B20%5E2%7D)
![10^{-4}=\dfrac{r_2^2}{20^2}](https://tex.z-dn.net/?f=10%5E%7B-4%7D%3D%5Cdfrac%7Br_2%5E2%7D%7B20%5E2%7D)
r₂ = 0.2 m