The source of Earth's magnetic field is
2 answers:
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Answer:
20J
Explanation:
In a collision, whether elastic or inelastic, momentum is always conserved. Therefore, using the principle of conservation of momentum we can first get the final velocity of the two bodies after collision. This is given by;
m₁u₁ + m₂u₂ = (m₁ + m₂)v ---------------(i)
Where;
m₁ and m₂ are the masses of first and second objects respectively
u₁ and u₂ are the initial velocities of the first and second objects respectively
v is the final velocity of the two objects after collision;
From the question;
m₁ = 2.0kg
m₂ = 8.0kg
u₁ = 5.0m/s
u₂ = 0 (since the object is initially at rest)
<em>Substitute these values into equation (i) as follows;</em>
(2.0 x 5.0) + (8.0 x 0) = (2.0 + 8.0)v
(10.0) + (0) = (10.0)v
10.0 = 10.0v
v = 1m/s
The two bodies stick together and move off with a velocity of 1m/s after collision.
The kinetic energy(KE₁) of the objects before collision is given by
KE₁ = m₁u₁² +
m₂u₂² ---------------(ii)
Substitute the appropriate values into equation (ii)
KE₁ = ( x 2.0 x 5.0²) + (
x 8.0 x 0²)
KE₁ = 25.0J
Also, the kinetic energy(KE₂) of the objects after collision is given by
KE₂ = (m₁ + m₂)v² ---------------(iii)
Substitute the appropriate values into equation (iii)
KE₂ = ( 2.0 + 8.0) x 1²
KE₂ = 5J
The kinetic energy lost (K) by the system is therefore the difference between the kinetic energy before collision and kinetic energy after collision
K = KE₂ - KE₁
K = 5 - 25
K = -20J
The negative sign shows that energy was lost. The kinetic energy lost by the system is 20J
Answer:
The answer is .
Explanation:
From the law of gravity,
considering F as a conservative force, ,
the general expression for gravitational potential energy is
,
where G is the gravitational constant, M and m are the mass of the attracting bodies, and r is the distance between their centers. The negative sign is because the force approaches zero for large distances, and we choose the zero of gravitational potential energy at an infinite distance away.
However, as the mass of the Sun is much greater than the mass of the rock, the gravitational acceleration is defined as
,
(the negative sign indicates that the force is an attractive force), and the potential energy between the rock and the Sun is
,
which is actually the total energy of the system, because the rock materializes stationary at this point (there is no radial kinetic energy).
When the rock hits the surface of the Sun, almost all potential energy is converted to kinetic energy, but not all because the Sun is not a puntual mass. So the potential energy converted to kinetic energy is
,
then, the kinetik energy when the rock hits the surface is
,
so
where g is the gravitational acceleration generated by the Sun at R,
.