26. Suppose a car travels 108 km at a speed of 30.0 m/s, and uses 2.0 gal of gasoline. Only 30% of the gasoline goes into useful work by the force that keeps the car moving at constant speed despite friction. (The energy content of gasoline is about 140 MJ/gal.) (a) What is the magnitude of the force exerted to keep the car moving at constant speed

F = 777.78N

The magnitude of the force exerted to keep the car moving at constant speed is 777.78N

Explanation:

Given;

Total distance travelled d = 108km = 108000m

Speed v = 30 m/s

Gasoline used a = 2 gal

Efficiency e = 30% = 0.3

Energy content C= 140MJ/gal

Energy used in moving the car at constant speed v is ;

E = eaC = efficiency × gasoline used × Energy content

Substituting the values;

E = 0.3×2×140MJ

E = 84MJ

Force = Energy/distance

F = E/d = 84 MJ ÷ 108km = 84 × 10^6 J ÷ 108000m

F = 777.78N

The magnitude of the force exerted to keep the car moving at constant speed is 777.78N

probably not the "magnets"in the magnet, so to speak, are thought to be electrons orbiting in shells. vurrent loops two sides to the loop

3. dark matter

empty space could also be a simple vacuum