Answer:9.75 m/s
Explanation:
Given
Length of ladder 
Foot the ladder is moving away with speed of 
From diagram
------1
at 


Now differentiating equation 1 w.r.t time




negative indicates distance is decreasing with time
Answer:
No, it is not necessary for them to have same mass.
Explanation:
Let both bodies have a density d1 and d2 respectively.
Since their volumes are equal V1 = V2
we know that, https://tex.z-dn.net/?f=%5Cfrac%7Bmass%7D%7Bvolume%7D
Hence, d1 = and d2 =
Taking the ratio of densities,we get
This implies that unless the bodies have same densities, the mass of the two bodies will not be same.
The ones that interact would be Atmosphere, biosphere, and cryosphere. :)
This behavior helps Betty in <u>intellectual </u>development.
The length of a vector arrow represents an magnitude