Answer:
For Total energy and momentum to be conserved, the minimum energy of the photons released is equal to twice the rest mass energy of an electron that is
The annihilation of electron -positron cannot produce a single photon. It is prohibited by the law of conservation of energy and momentum.
Answer:
a)
b)
c)
Explanation:
a) Immediately after the rod is released, <u>the rod is still horizontal but now subject to gravity.</u> Since one end of the rod is fixed, then the weight of the rod applies a torque. Then by Newton's Second Law, the acceleration can be found.
where I is the moment of inertia of the rod with respect to its fixed end, and α is the angular acceleration.
The net torque of the rod is
where r is the distance from center of the mass to the fixed end, so r = 0.4 m.
The weight of the rod is w = mg = 0.26 x 9.8 = 2.54 N.
So the net torque is τ = 1.01 Nm.
The moment of inertia of the rod is
So, the Newton's Second Law yields
<u>The relation between angular acceleration and linear acceleration is a = αr </u>
So, the linear acceleration of the rod is
b) Using the same relationship between angular acceleration and linear acceleration, the linear acceleration of the end of the rod can be found.
c) The conservation of energy can be used to find the velocity when the rod is vertical.
The linear velocity is v = ωr, so
v = 2.43 m/s.