Answer:
Vr = 20 [km/h]
Explanation:
In order to solve this problem, we have to add the relative velocities. We must remember that velocity is a vector, therefore it has magnitude and direction. We will take the sea as the reference measurement level.
Let's take the direction of the ship as positive. Therefore the boy moves in the opposite direction (Negative) to the reference level (the sea).
1) See three Kepler laws below
2a) Acceleration is
2b) Tension in the string: 27.4 N
3a) Kinetic energy is the energy of motion, potential energy is the energy due to the position
3b) The kinetic energy of the object is 2.25 J
Explanation:
1)
There are three Kepler's law of planetary motion:
2a)
To solve the problem, we have to write the equation of motions for each block along the direction parallel to the incline.
For the block on the right, we have:
(1)
where
is the component of the weight of the block parallel to the incline, with
M = 8.0 kg (mass of the block)
(acceleration of gravity)
T = tension in the string
a = acceleration of the block
For the block on the left, we have similarly
(2)
where
m = 3.5 kg (mass of the block)
From (2) we get
Substituting into (1),
Solving for a,
2b)
The tension in the string can be calculated using the equation
where
m = 3.5 kg (mass of lighter block)
(acceleration found in part 2)
Substituting,
3a)
The kinetic energy of an object is the energy due to its motion. It is calculated as
where
m is the mass of the object
v is its speed
The potential energy is the energy possessed by an object due to its position in a gravitational field. For an object near the Earth's surface, it is given by
where
m is the mass of the object
g is the strength of the gravitational field
h is the heigth of the object relative to the ground
3b)
The kinetic energy of an object is given by
where
m is the mass of the object
v is its speed
For the object in this problem,
m = 500 g = 0.5 kg
v = 3 m/s
Substituting, we find its kinetic energy:
Learn more about acceleration and forces:
And about kinetic energy:
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