According to the right-hand thumb rule, the forefinger gives the velocity of charge, the thumb gives the magnetic force and the center finger gives the direction of magnetic field.
then, as shown in the picture, the <span>direction of the magnetic force on the charge is in the right direction.</span>
6: Short way: it cannot be 2.5, 3, or 5 because up to 5 seconds it only has positive velocity so it must be moving forwards.
Long Way: Velocity is in m / s, multiply that by time (s) to get m or displacement. From 0->5 you have a triangle under the curve, (1/2)(5)(20) = 50 meters displaced positive, you need to then look when velocity is under the curve and use a similar equation to solve for the area but make the answer negative. Find the point where it equals -50 and that is where it will have returned.
Answer to 6: B
7. I cannot see the problem enough to answer this. Just know if the line is above 0 velocity is positive so it is moving the direction it started, when it goes below 0 velocity is negative so it is moving opposite direction it started.
8. Accelration is change in velocity. Whatever the slope of the velocity graph is acceleration. At t=8 the slope is 0 because it is not going up or down.
Answer to 8: A
Classically and Newtonianly, it's the sum of the chemical energy if any,
the electrical energy if any, the thermal energy if any, and the mechanical
energy consisting of potential and kinetic energy if any.
The mechanical energy, consisting of potential and kinetic energy if any, is
0.001 x [ (acceleration of gravity x height) + (1/2) (speed)² ] .
But I've got a sneaky hunch that you're not talking about any of these.
You want to know how much [ <em><u>mc</u>² </em>] there is in 1 gram of mass. No prob.
E = m c² = (0.001) x (3 x 10⁸)² = <em>9 x 10¹³ joules</em>
That's the energy that a 1,000-watt toaster uses
in <em>2,852 years</em> of continuous toasting.
