Which statement correctly describes mass-energy equivalence? All energy in the universe will be converted to an equivalent amoun
1 answer:
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The work done is 375 J
Explanation:
The work done by a force in moving an object is given by
where
F is the magnitude of the force
d is the displacement
is the angle between the direction of the force and the displacement
In this problem,
F = 75 N is the force applied to the couch
d = 5 m is the displacement
Assuming the force applied to the couch is parallel to the motion,
And so, the work done is
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Answer:
Speed of the ball relative to the boys: 25 km/h
Speed of the ball relative to a stationary observer: 35 km/h
Explanation:
The RV is travelling at a velocity of
Here we have taken the direction of motion of the RV as positive direction.
The boy sitting near the driver throws the ball back with speed of 25 km/h, so the velocity of the ball in the reference frame of the RV is
with negative sign since it is travelling in the opposite direction relative to the RV. Therefore, this is the velocity measured by every observer in the reference frame of the RV: so the speed measured by the boys is
v = 25 km/h
Instead, a stationary observer outside the RV measures a velocity of the ball given by the algebraic sum of the two velocities:
v = +60 km/h + (-25 km/h) = +35 km/h
So, he/she measures a speed of 35 km/h.