The answer is 8 because multiplying 7 and 8 is 56
Answer:
(a) 
(b) 
(c) 
Explanation:
Given that,
(a) An electron accelerated from rest through a potential difference of 100 V. The De Broglie wavelength in terms of potential difference is given by :

Where
m and e are the mass of and charge on an electron
On solving,

V = 100 V


(b) V = 1 kV = 1000 V



(c) If 


Hence, this is the required solution.
Resolution in this sentence refers to a solution to the problem
Answer:
1.15 rad/s²
Explanation:
given,
angular speed of turntable = 45 rpm
=
=
time, t = 4.10 s
initial angular speed = 0 rad/s
angular acceleration.



Hence, the angular acceleration of the turntable is 1.15 rad/s²
The mistake here is that the total energy of the system does not change - generally, the total amount of energy in a system never changes unless the energy enters or leaves the system somehow (for example, if you see the Earth alone as a system, then energy from the sun enters the system and some energy is lost to space in the form of heat).