The kinetic energy of an object of mass m and velocity v is given by

Let's call

the initial speed of the car, so that its initial kinetic energy is

where m is the mass of the car.
The problem says that the car speeds up until its velocity is twice the original one, so

and by using the new velocity we can calculate the final kinetic energy of the car

so, if the velocity of the car is doubled, the new kinetic energy is 4 times the initial kinetic energy.
Explanation:
The particle will be at rest when its velocity
is equal to zero. Recall that the velocity is simply the derivative of the position
with respect to time:

Since 
then

Solving for t, we find that the particle will be at rest at

Answer:

Explanation:
<u>Displacement</u>
It is a vector that points to the final point where an object traveled from its starting point. If the object traveled to several points, then the individual displacements must be added as vectors.
The mail carrier leaves the post office and drives 2 km due north. The first displacement vector is

Then the carrier drives 7 km in 60° south of east. The displacement has two components in the x and y axis given by

Finally, he drives 9.5 km 35° north of east.

The total displacement is


The direction can be calculated with


Answer:
a. Fr^2 = 119.7^2 + 49.9^2 = 16,818.1
Fr = 129.7 N.
b. tanA = Y/X = 49.9/119.7 = 0.41688
A = 22.63o = Direction.
Explanation: