The box is kept in motion at constant velocity by a force of F=99 N. Constant velocity means there is no acceleration, so the resultant of the forces acting on the box is zero. Apart from the force F pushing the box, there is only another force acting on it in the horizontal direction: the frictional force
which acts in the opposite direction of the motion, so in the opposite direction of F.
Therefore, since the resultant of the two forces must be zero,
so
The frictional force can be rewritten as
where
,
. Re-arranging, we can solve this equation to find
, the coefficient of dynamic friction:
Refer to the diagram shown below.
R = total resistive force.
80% of this force is experienced by the boat and trailer.
T = the force in the hitch between the car and the trailer.
Overall motion:
Total mass = 1100 + 700 = 1800 kg
Acceleration = 0.55 m/s²
Driving force = 1900 N
Resisting force = R N
Therefore
(1900 - R N) = (1800 kg)*(0.55 m/s²)
1900 - R = 990
R = 910 N
0.2R = 182 N
0.8R = 728 N
Consider the motion of the car:
Driving force = 1900 N
Resistive force = 0.2R = 182 N
Force in the hitch = T NAcceleration = 0.55 m/s²
Mass = 1100 kg
Therefore
1900 - 0.2R - T = 1100*0.55
1900 - 182 -T = 605
T = 1113 N
Answer:
R = 910 N, the total resistive force.
T = 1113 N, the force in the hitch between the car and trailer.
(a) the three resistors are in parallel, so the equivalent resistance R is given by
1/R= 1/5 + 1/10 +1/15
1/R= 11/30
R=2.7ohm
(b) Voltage in the circuit= 120 V
(c) for current, we use ohm's law
V= i R
120= i (2.7)
i=44 A
Explanation:
It is given that,
A helicopter blade spins at exactly 100 revolutions per minute.
Its tip is 5.00 m from the center of rotation, r = 5 m
(a) Let v is the average speed of the blade tip in the helicopter’s frame of reference. Distance covered by the helicopter, 
In 100 revolutions, 
So, average speed of the blade tip in one second is given by :
v = 52.35 m/s
(b) The average velocity over one revolution is zero because the net displacement in one rotation is 0.
Hence, this is the required solution.
Answer:
The average speed would be the 200 miles/4 hours.
The average velocity would be the net displacement to the north at 80 miles/4 hrs = mph
Explanation:
