The equation for kinetic energy is,
Ke = (1/2)mv^2.
You're given a kinetic energy of 790 joules, and a speed of 1.6 m/s. Plugging these values into the equation, we get,
790 = (1/2)(1.6)^2(m).
Solving for m, we get,
m = (790)/(0.5(1.6)^2).
I'll let you crunch out those numbers for yourself :D
If you have any questions, feel free to ask. Hope this helps!
Let's see: frequency of cellular phone waves (GSM phones) is (800-1900 MHz). If we look at the table of the electromagnetic spectrum, we can see that this range is contained within the frequencies of the microwaves, which include waves in the range 300 MHz-300 GHz.
So, summarizing, the correct answer is "microwaves".
According to the conservation of mechanical energy, the kinetic energy just before the ball strikes the ground is equal to the potential energy just before it fell.
Therefore, we can say KE = PE
We know that PE = m·g·h
Which means KE = m·g·h
We can solve for h:
h = KE / m·g
= 20 / (0.15 · 9.8)
= 13.6m
The correct answer is: the ball has fallen from a height of 13.6m.
Answer:
<em>The force of kinetic friction between Kiera and the floor is 9.24 N</em>
Explanation:
<u>Friction Force</u>
When an object is moving and encounters friction in rough surfaces, it loses acceleration and/or velocity because the friction force opposes motion.
The friction force when an object is moving on a horizontal surface is calculated by:

Where μ is the coefficient of static or kinetics friction and N is the normal force.
If no forces other then the weight and the normal are acting upon the y-direction, then the weight and the normal are equal in magnitude:
N = W
Thus, the friction force is:

Kiera, the W=330 N girl steps in water that has a coefficient of friction of μ=0.028 with the floor.
The kinetic friction force is:
Fr = 0.028*330
Fr = 9.24 N
The force of kinetic friction between Kiera and the floor is 9.24 N