Explanation:
It is given that,
Uncertainty in the speed of an electron, 
According to Heisenberg uncertainty principle,

is the uncertainty in the position of an electron
Since, 



So, the uncertainty in its position is
. Hence, this is the required solution.
Answer:
A) A warm wire
Explanation:
A warm wire has the most resistance. Heating the metal wire causes atoms to vibrate more, which in turn makes it more difficult for the electrons to flow, increasing resistance. Heating the wire increases resistivity.
Answer:
Explanation:
spring constant k = 425 N/m
a ) At the point of equilibrium
restoring force = frictional force
= kx = 10 N
425 x = 10
x = 2.35 cm
b )
Work done by frictional force
= -10 x 2.35 x 10⁻² x 2 J ( Distance is twice of 2.35 cm )
= - 0.47 J
= Kinetic energy remaining with the cookie as it slides back through the position where the spring is unstretched .
= 425 - 0.47
= 424.53 J
=
Answer:
The duration of the movie is longer than 2 hrs.
Explanation:
Given:
The duration of the movie observed by the crew on the spacecraft is 2 hrs.
According to time-dilation formula:

Here,
is the required time,
is the original time,
is the velocity of the spacecraft and
is the velocity of light.
Since
, so
.
So the time required will be large.
Answer:
Approximate atomic radius for polonium-209 is 167.5 pm .
Explanation:
Number of atom in simple cubic unit cell = Z = 1
Density of platinum = 
Edge length of cubic unit cell= a = ?
Atomic mass of Po (M) = 209 g/mol
Formula used :

where,
ρ = density
Z = number of atom in unit cell
M = atomic mass
= Avogadro's number
a = edge length of unit cell
On substituting all the given values , we will get the value of 'a'.


Atomic radius of the polonium in unit cell = r
r = 0.5a



Approximate atomic radius for polonium-209 is 167.5 pm.