One well-known application of density is determining whether or not an object will float on water. If the object's density is less than the density of water, it will float; if its density is less than that of water, it will sink.In fact, submarines dive below the surface of the water by emptying their ballast tanks
The acceleration should 5.4 m/s^2
Mechanical and electrical
Answer:
610 meters.
Explanation:
Because Jim released the accelerator, the truck started to slow down, so the friction force will eventually stop the truck.
the kinetic energy of the truck just after Jim released the pedal is:

The work done by the friction force is given by:

Convert 38 ft/s^2 to mi/h^2. Then we se the conversion factor > 1 mile = 5280 feet and 1 hour = 3600 seconds.
So now we show it > 
Then we have to use the formula of constant acceleration to determine the distance traveled by the car before it ended up stopping.
Which the formula for constant acceleration would be > 
The initial velocity is 50mi/h 
When it stops the final velocity is 
Since the given is deceleration it means the number we had gotten earlier would be a negative so a = -93272.27
Then we substitute the values in....

So we can say the car stopped at 0.0134 miles before it came to a stop but to express the distance traveled in feet we need to use the conversion factor of 1 mile = 5280 feet in otherwards > 
So this means that the car traveled in feet 70.8 ft before it came to a stop.