A sinusoidal electromagnetic wave from a radio station passes perpendicularly through an open window that has area 0.320 m2. at
1 answer:
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1) The mass of the continent is
2) The kinetic energy of the continent is 274.8 J
3) The speed of the jogger must be 2.76 m/s
Explanation:
1)
The continent is a slab of side 5900 km (so the surface is 5900 x 5900, assuming it is a square) and depth 26 km, therefore its volume is:
The mass of the continent is given by
where:
is its density
is its volume
Substituting, we find the mass:
2)
To find the kinetic energy, we need to convert the speed of the continent into m/s first.
The speed is
v = 1.6 cm/year
And we have:
1.6 cm = 0.016 m
So, the speed is
Now we can find the kinetic energy of the continent, which is given by
where
is the mass
is the speed
Substituting,
3)
The jogger in this part has the same kinetic energy of the continent, so
K = 274.8 J
And its mass is
m = 72 kg
We can write his kinetic energy as
where
v is the speed of the man
And solving the equation for v, we find his speed:
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Solution :
Given :
M = 0.35 kg
Total mechanical energy = constant
or
But and
Therefore, potential energy at the top = kinetic energy at the bottom
(h = 35 cm = 0.35 m)
= 2.62 m/s
It is the velocity of M just before collision of 'm' at the bottom.
We know that in elastic collision velocity after collision is given by :
here,
∴
= 0.33 m/s
Therefore, velocity after the collision of mass M = 0.33 m/s