Answer:
there is no net force acting on the object
Explanation:
If an object is moving with a constant velocity, then by definition it has zero acceleration. So there is no net force acting on the object. The total work done on the object is thus 0 (that's not to say that there isn't work done by individual forces on the object, but the sum is 0 ).
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Explanation:
When a person is standing still, the forces acting on them (weight force pulling down and normal force pushing up) are equal and opposite, so the net force is balanced. So the person will continue to be at rest, unless the net force becomes unbalanced.
When a person falls with a parachute, the forces acting on them (weight force pulling down and air resistance pushing up) are equal and opposite, so the net force is balanced. So the person will continue to fall at the same speed until the net force becomes unbalanced.
Answer with Explanation:
We are given that
Mass of one body=4.5 kg
Initial velocity of one body=8.9 m/s
Initial velocity of another body=0
Final velocity of one body=
a.We have to find the mass of the other body.
Energy and momentum are conserved in this system
(equation I)
From conservation of kinetic energy
(equation II)
Substitute equation I in equation II
Substitute the given values then we get
Hence, the mass of other body=3 kg
b.We have to find the speed of two body center of mass .
The center of mass speed is given by
Substitute the values then we get
Hence, the speed of the two body center of mass is given by =5.34 m/s
Answer:
a)
b)
Explanation:
Let´s use Doppler effect, in order to calculate the observed frequency by the byciclist. The Doppler effect equation for a general case is given by:
where:
Now let's consider the next cases:
The data provided by the problem is:
The problem don't give us aditional information about the medium, so let's assume the medium is the air, so the speed of sound in air is:
Now, in the first case the observer alone is in motion towards to the source, hence:
Finally, in the second case the observer alone is in motion away from the source, so: