Answer:
The velocity of the boat with respect to the ground is 3 km/h
Explanation:
The speed of an object is different depending on the reference system you use. This is called relative speed.
A boat travels upstream, this means that it moves in the opposite direction to the river current.
A boat travels upstream, this means that it moves in the opposite direction to the river current. Then, if the boat moves in the positive direction of the x axis at 10 km / h with respect to the water of a river, the water flows in the negative direction of the x axis at 7 km / h with respect to the ground.
This causes the speed of the boat relative to the ground to be calculated as follows:
<em>VbG = Vbw - VwG
</em>
where VbG is the speed of the boat relative to the ground, Vbw is the speed of the boat relative to the water of the river and VwG is the speed of the water relative to the ground.
So: VbG=10 km/h – 7 km/h
<u><em>VbG= 3 km/h
</em></u>
The direction of this velocity is in the positive x-direction.
B. +Q, + W are the correct sign
Answer: when in doubt go with B
Explanation:
The sister suddenly pushes her brother. As a result, the sister moves with kinetic energy k. The resulting kinetic energy of the brother is k/2.
<h3>What is kinetic energy?</h3>
The ability of an object to do work by virtue of its motion is called the kinetic energy.
A brother and sister are standing next to each other at rest on a surface of frictionless ice. The brother’s mass is exactly twice that of his sister’s.
If the sister's mass is m, the brother's mass is 2m.
The kinetic energy of sister is k =1/2 mv²,
The velocity will also get halved for brother, So, the kinetic energy of brother will be
k' = 1/2 (2m)(v/2)²
On comparing, the relation between the kinetic energy of brother and sister is k' = k/2
Thus, the resulting kinetic energy of the brother is k/2.
Learn more about kinetic energy.
brainly.com/question/12669551
#SPJ4
When do you gotta turn it in?
