It is B since they are traveling at the same speed one is positive so the other had to be negative hope this helps;)))))
The angular acceleration of a rotating object is given by

where

is the final angular speed of the object

is its initial angular speed

is the time taken to accelerate
For the wheel in our problem,

,

and

, so its angular acceleration is
Answer:
(a) 
(b) 15 hours
Explanation:
half life, T = 12 hours
No = 19 g
(a) Let N be the amount remaining after time t.
Let λ be the decay constant.

The equation of radioactivity used here is given by


(b) N = 8 gram
Substitute the values in above equation

λ = 0.0577 per hour
So, 

Take natural log on both the sides
- 0.0577 t = - 0.865
t = 15 hours
Answer:
λ = 65.6 pm
Explanation:
Given that
λo = 65 pm
The initial energy of the electron

Now by putting the values




Eo=19.06 KeV
Given that kinetic energy KE= 0.84 KeV
Therefore the final energy
E= Eo - KE
E = 19.06 - 0.84 KeV
E= 18.22 KeV
The wavelength λ can be find as



λ = 6.56 x 10⁻¹¹ m
λ = 65.6 pm