We can use Newton II here (where F=m*a), that F is the net (or resultant) force on the object, m is the mass of the object and a is the acceleration the object experiences.
This means, in this case there would be no friction and absolutely no other force which gives a component in the plane of motion, only then can you assume that F=804N.
Now using F= m*a
804 = 51.7*a
Therefore a = 804/51.7 = 15.55 m/s²
Answer:

Explanation:
= Permittivity of free space = 
A = Area
h = Altitude = 600 m
Electric flux through the top would be
(negative as the electric field is going into the volume)
At the bottom

Total flux through the volume

Electric flux is given by

Charge per volume is given by

The volume charge density is 
The words "... as shown ..." tell us that there's a picture that goes along
with this question, and you decided not to share it. That's sad and
disappointing, but I think the question can be answered without seeing
the picture.
The net force on the crate is zero. Evidence for this is that fact that
the crate is just sitting there. If the net force on an object is not zero,
then the object is accelerating ... it's either speeding up, slowing down,
or its the direction of its motion is changing. If none of these things is
happening, then the net force on the object must be zero.
Answer:
The energy that the truck lose to air resistance per hour is 87.47MJ
Explanation:
To solve this exercise it is necessary to compile the concepts of kinetic energy because of the drag force given in aerodynamic bodies. According to the theory we know that the drag force is defined by

Our values are:




Replacing,


We need calculate now the energy lost through a time T, then,

But we know that d is equal to

Where
v is the velocity and t the time. However the time is given in seconds but for this problem we need the time in hours, so,

(per hour)
Therefore the energy that the truck lose to air resistance per hour is 87.47MJ
Answer:
h = 0.46 m
Explanation:
According to the law of conservation of energy:
Potential Energy Lost by Roller Coaster = Kinetic Energy Gained by Roller Coaster

where,
h = height = ?
v = speed at bottom = 3 m/s
g = acceleration due to gravity = 9.81 m/s²
Therefore,

<u>h = 0.46 m</u>