Answer:
D
The answer cannot be found until it is known whether q is greater than, less than, or equal to 45°.
Explanation:
Since block moves with constant speed
So, frictional force
f = FCosq
Work done by friction
W = - fd
W = - fd Cos q
The answer may be greater or less than - fdSinq. It depends on the value of q which is less than, or equal to 45°.
Answer:
Explanation:
Given
Wall is
in area
requires 1 gallon of paint
so using unitary method
gallon of paint
wall will require
gallons of paint

Answer:
Explanation:
Given
length of wire 
change in length 
mass of wire 
Young's modulus for silver 
load on wire 

change in length is given by

Where A=area of cross-section




also wire is the shape of cylinder so cross-section is given by





It produces only virtual images is the answer
Answer:

Explanation:
Let the mass of copper ball is "m" gram
now the total number of copper atom present in the ball is given as

now the total number of electrons in one copper atom is 29
so total number of electrons in given sample of copper ball is

now diameter of the ball is 7.0 mm
density of the ball = 
now we have



now we have

now the charge on the copper ball is 40 nC
so the number of electrons removed



so the fraction of number of electrons removed is given as


