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:
-5 V
Explanation:
The charged particle (which is positively charged) moves from point A to B, and its kinetic energy increases: it means that the particle is following the direction of the field, so its potential energy is decreasing (because it's been converted into potential energy), therefore it is moving from a point at higher potential (A) to a point at lower potential (B). This means that the value
vb−va
is negative.
We can calculate the potential difference between the two points by using the law of conservation of energy:
where:
is the change in kinetic energy of the particle
is the charge of the particle
is the potential difference
Re-arranging the equation, we can find the value of the potential difference: