Answer:
The frictional force 
6.446 N
The acceleration of the block a = 6.04 
Explanation:
Mass of the block = 3.9 kg
°
= 0.22
(a). The frictional force is given by
3.9 × 9.81 × 
29.3 N
Therefore the frictional force
0.22 × 29.3
6.446 N
(b). Block acceleration is given by
F = 30 N
= 6.446 N
= 30 - 6.446
= 23.554 N
The net force acting on the block is given by
23.554 = 3.9 × a
a = 6.04
This is the acceleration of the block.
Not exactly the best way to describe it but, it is used to calculate resistance of a lever as in the use of a pry bar or pulley. Technology used to increase output with little input.
<span>First law of thermodynamics. This conservation law states that energy cannot be created or destroyed but can be changed from one form to another. In essence, energy is always conserved but can be converted from one form into another. Like when an engine burns fuel, it converts the energy stored in the fuel's chemical bonds into useful mechanical energy and then into heat, or more specifically, the melting ice cubes. Yeast breaks down maltose into glucose to produce alcohol and Co2 in the fermentation process. This is a prime example of the 1st law of thermodynamics. No form of usable energy is really lost; it only changes from one form to another</span>
Explanation:
∆x=300 m×2
∆t=1.5 s
v=∆x/∆t → v=2×300/1.5 = 400 m/s
C is what i always have so ima go with C.
