Answer:
(a) the time needs for her to cross the river is 2736.8 s.
(b) the distance takes to reach the other side of the river is 2490.5 m.
Explanation:
given information:
woman's speed, v₁ = 1.9 m/s
the wide of river, s = 5.2 km = 5200 m
river's current, v₂ = 0.91 m/s
(a) How much time does it take her to cross the river?
s = v t
s = the displacement (m)
v = speed (m/s)
t = time (s)
s = v t
t = s/v
= 5200/1.9
= 2736.8 s
(b) How far downstream will the river carry her by the time she reaches the other side of the river?
s = v t
= (0.91) (2736.8)
= 2490.5 m
Answer:
12 km/h
Explanation:
Average Speed = Distance / Time (or rate)
Pick a point on the graph for Ian and plug in values.
For example, 20 minutes -> 4km
Hence, Average speed = 4km ÷ 20 minutes = 0.2 km/min
0.2 km/min × 60 = 12 km/h
The electron is accelerated through a potential difference of
, so the kinetic energy gained by the electron is equal to its variation of electrical potential energy:
where
m is the electron mass
v is the final speed of the electron
e is the electron charge
is the potential difference
Re-arranging this equation, we can find the speed of the electron before entering the magnetic field:
Now the electron enters the magnetic field. The Lorentz force provides the centripetal force that keeps the electron in circular orbit:
where B is the intensity of the magnetic field and r is the orbital radius. Since the radius is r=25 cm=0.25 m, we can re-arrange this equation to find B:
<span>In order to determine the speed of the entire assembly, we employ conservation of momentum. Momentum p = mv where m is the object's mass and v is the velocity.
The putty ball's initial momentum p1 = 0.3kg*6m/s = 1.8 kg*m/s
That momentum is conserved, so the momentum of the new system having mass 0.3 kg + 1.2 kg = 1.5 kg is:
1.8 kg*m/s = 1.5kg*v. Solving for v, we find that the velocity is 1.2 meters/second.</span>
During the ball's flight up its velocity and acceleration vectors are in opposite direction and during the ball's flight down its velocity and acceleration vectors are in same direction.
- The velocity vector is always in the direction of motion of the object. So, during the ball's flight up its velocity vector is in the upward direction (90°) and during the ball's flight down its velocity vector is in the downward direction (270°).
- When there is a positive acceleration in the object the acceleration vector is in the direction of motion of the object. When there is a negative acceleration in the object the acceleration vector is in the opposite direction of motion of the object. So, during the ball's flight up its acceleration vector is in the downward direction (270°) and during the ball's flight down its acceleration vector is in the upward direction (90°).
Velocity vector is the rate of change of position of an object. Acceleration vector is the rate of change of velocity of an object.
Therefore, during the ball's flight up its velocity and acceleration vectors are in opposite direction and during the ball's flight down its velocity and acceleration vectors are in same direction.
To know more about velocity and acceleration vectors
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