The kinetic energy of the electron is

where

is the mass of the electron and v its speed. Since we know the value of the kinetic energy,

, we can find the value of the speed v:
One reason that it would be appropriate to talk on your cell phone, could be reporting an accident. For instance, a car crash, a sign in the road anything regarding safety of drivers.
Explanation:
The distance that a car travels down the interstate can be calculated with the following formula:
Distance = Speed x Time
(A) Speed of the car, v = 70 miles per hour = 31.29 m/s
Time, d = 6 hours = 21600 s
Distance = Speed x Time
D = 31.29 m/s × 21600 s
D = 675864 meters
or

(b) Time, d = 10 hours = 36000 s
Distance = Speed x Time
D = 31.29 m/s × 36000 s
D = 1126440 meters
or

(c) Time, d = 15 hours = 54000 s
Distance = Speed x Time
D = 31.29 m/s × 54000 s
D = 1689660 meters
or

Hence, this is the required solution.
The question is incomplete. Here is the complete question.
Three crtaes with various contents are pulled by a force Fpull=3615N across a horizontal, frictionless roller-conveyor system.The group pf boxes accelerates at 1.516m/s2 to the right. Between each adjacent pair of boxes is a force meter that measures the magnitude of the tension in the connecting rope. Between the box of mass m1 and the box of mass m2, the force meter reads F12=1387N. Between the box of mass m2 and box of mass m3, the force meter reads F23=2304N. Assume that the ropes and force meters are massless.
(a) What is the total mass of the three boxes?
(b) What is the mass of each box?
Answer: (a) Total mass = 2384.5kg;
(b) m1 = 915kg;
m2 = 605kg;
m3 = 864.5kg;
Explanation: The image of the boxes is described in the picture below.
(a) The system is moving at a constant acceleration and with a force Fpull. Using Newton's 2nd Law:




Total mass of the system of boxes is 2384.5kg.
(b) For each mass, analyse each box and make them each a free-body diagram.
<u>For </u>
<u>:</u>
The only force acting On the
box is force of tension between 1 and 2 and as all the system is moving at a same acceleration.


= 915kg
<u>For </u>
<u>:</u>
There are two forces acting on
: tension caused by box 1 and tension caused by box 3. Positive referential is to the right (because it's the movement's direction), so force caused by 1 is opposing force caused by 3:


= 605kg
<u>For </u>
<u>:</u>


= 864.5kg
It could possibly melt things