Answer:
33.2 m/s
Explanation:
In order to solve this problem, we need to know the mass of the car.
Here, we assume that the mass of the car is
m = 1 kg
Then, we can apply the work-energy theorem, which states that the work done on the car by the braking force is equal to the change in its kinetic energy:
where:
F = -3.87 N is the force applied by the brakes (negative because its direction is opposite to the motion of the car)
d = 4.92 m is the displacement of the car
u = 33.8 m/s is the initial velocity of the car
v is the final velocity of the car
Therefore, solving for v, we find:
Answer: 4.8 s
Explanation:
We have the following data:
the mass of the raft
the force applied by Sawyer
the raft's final speed
the raft's initial speed (assuming it starts from rest)
We have to find the time
Well, according to Newton's second law of motion we have:
(1)
Where is the acceleration, which can be expressed as:
(2)
Substituting (2) in (1):
(3)
Where
Isolating from (3):
(4)
Finally:
Answer:
(a)
(b)
Explanation:
(a) The surface current density of a conductor is the current flowing per unit length of the conductor.
Considering a wire, the current is uniformly distributed over the circumferenece of the wire.
The radius of the wire = a
The surface current density
(b) The current density is inversely proportional
......(1)
k is the constant of proportionality
........(2)
substituting (1) into (2)
substitute