Answer:
a) 3.43 m/s
Explanation:
Due to the law of conservation of momentum, the total momentum of the bullet - rifle system must be conserved.
The total momentum before the bullet is shot is zero, because they are both at rest, so:

Instead the total momentum of the system after the shot is:

where:
m = 0.006 kg is the mass of the bullet
M = 1.4 kg is the mass of the rifle
v = 800 m/s is the velocity of the bullet
V is the recoil velocity of the rifle
The total momentum is conserved, therefore we can write:

Which means:

Solving for V, we can find the recoil velocity of the rifle:

where the negative sign indicates that the velocity is opposite to direction of the bullet: so the recoil speed is
a) 3.43 m/s
A is not the correct answer because the amplitude and oscillation and there is 1/2 A in oscillation
Answer and explanation;
-The cause of convention currents in a hot spring is rainwater and melted snow is cool and denser and sinks to the bottom of the hot spring where it is heated by a shallow magma chamber. The heated water expands and is less dense and rises to the top.
Explanation;
-Convention Current is the movement of fluid caused by the differences in temperature. Transference of heat from one part of a fluid to another.
-Lighter (less dense), warm material rises while heavier (more dense) cool material sinks. It is this movement that creates circulation patterns known as convection currents in the atmosphere, in water, and in the mantle of Earth. In the atmosphere, as air warms it rises, allowing cooler air to flow in underneath.
FOR THAT YOU NEED TO UNDERSTAND WHAT ACTUALLY KINETIC ENERGY IS.
It is a form of energy which is caused due to motion, when the ball is kicked, it is send into motion thus it gains kinetic energy, how come energy came from ? as you have already read this ENERGY MASS CANT BE CREATED OR DESTROYED. In this scenario the energy is being transferred by the football player into the ball which appears as the kinetic energy of the ball... that's how it works