Answer:

Explanation:
Torque is defined as the cross product between the position vector ( the lever arm vector connecting the origin to the point of force application) and the force vector.

Due to the definition of cross product, the magnitude of the torque is given by:

Where
is the angle between the force and lever arm vectors. So, the length of the lever arm (r) is minimun when
is equal to one, solving for r:

Answer:
C?
Explanation:
My best guess would be C as it's the only answer that gives a reason behind the statement.
Answer:
A) 199.78 J
B) 9.292x10^14 J
C) 4.2x10^7 m/s
D) 0.65 m
E) 1.13x10^-8 sec
D) 2.94x10^-9 sec
Explanation:
mass of ball = 0.0580 kg
A)
If smashed at v = 83.0 m/s, KE is
KE = 0.5mv^2
= 0.5 x 0.0580 x 83.0^2
= 199.78 J
B) if returned at v = 1.79×10^8 m/s, KE will be
KE = 0.5mv^2
= 0.5 x 0.0580 x (1.79×10^8)^2
= 9.292x10^14 J
C) during Einstein's return, velocity of rabbit relative to players is
Vr = 2.21×108 m/s
Rabbit's velocity relative to ball = 2.21×10^8 - 1.79×10^8
= 4.2x10^7 m/s
D) the rabbit's speed approaches the speed of light so we consider relativistic effect. The rabbit's measured distance is
l = l°( 1 - v^2/c^2)
= 2.5(1 - 2.21/3)
= 2.5 x 0.26
= 0.65 m
E) according to the players, the time taken by the rabbit is
t = d/v = 2.5/ 2.21×10^8
= 1.13x10^-8 sec
F) the time for rabbit as measured by rabbit is relativistic
t = t°( 1 - v^2/c^2)
= 1.13x10^-8 (1 - 2.21/3)
= 1.13x10^-8 x 0.26
= 2.94x10^-9 sec
Answer:
(a) 
(b) neither increasing or decreasing
(c) opposite to the flow of charge carriers
Explanation:
The current through an inductor of inductance L is given by:
(1)
(a) The induced emf is given by the following formula
(2)
You derivative the expression (1) in the expression (2):

(b) At t=0 the current is zero
(c) At t = 0 the emf is:

w, L and Imax have positive values, then the emf is negative. Hence, the induced emf is opposite to the flow of the charge carriers.
(d) read the text carefully