Answer:
Case A
Explanation:
given,
size of bacteria = 1 mm x 1 mm
velocity = 20 mm/s
size of the swimmer = 1.5 m x 1.5 m
velocity of swimmer = 3 m/s
Viscous force

for the bacteria


for the swimmer


from the above force calculation
In case B inertial force that represent mass is more than the inertial force in case of bacteria.
Viscous force is dominant in case of bacteria.
So, In Case A viscous force will be dominant.
Answer:
The new resistance becomes half of the initial resistance.
Explanation:
The resistance of a wire is given by :

= resistivity of material
L and A are linear dimension
If the electrical wire is replaced with one having every linear dimension doubled i.e. l' = 2l and r' = 2r
New resistance of wire is given by :




The new resistance becomes half of the initial resistance. Hence, this is the required solution.
Answer:
(a) k =
(b) τ =
∝
Explanation:
The moment of parallel pipe rotating about it's axis is given by the formula;
I =
---------------------------------1
(a) The kinetic energy of a parallel pipe is also given as;
k =
--------------------------------2
Putting equation 1 into equation 2, we have;
k = 
k =
(b) The angular momentum is given by the formula;
τ = Iw -----------------------3
Putting equation 1 into equation 3, we have
τ = 
But
τ = dτ/dt =
------------------4
where
dw/dt = angular acceleration =∝
Equation 4 becomes;
τ =
∝
Answer:
Its traveling in the +x direction
Explanation:
The E-field is in the +y-direction, and the B-field is in the +z-direction, so it must be moving along the +x-direction, since the E-field, B-field and the direction of moving are all at right angles to each other.