A person ran with a speed of 6 m/s onto the skateboard .What is the speed with which he ride on the skate board

First, remember the conservation of energy.

We can define the kinetic energy as:

K = (1/2)*m*v^2

where m is the mass, and v is the velocity.

The velocity of the person is 6m/s, and the mass is unknown.

Now, when the person rides the skateboard, this kinetic energy must remain constant, if M is the mass of the skateboard, the speed after the person rides ir will be:

K' = (1/2)*(m + M)*v'^2

Where v' is the new velocity.

In this case, we can suppose that the skateboard has really small mass compared with the person.

M < < m

then:

(m + M) ≈ m

then:

K' = (1/2)*m*v'^2 = K = (1/2)*m*v^2

from that equation, we can conclude that:

v' = v

Then if the velocity before riding the skateboard was 6m/s, then after would be also 6m/s.

specific latent heat of fusion, lf, of a substance is defined as the amount of heat required to change a unit mass of the substance from solid to liquid state, without any change in the temperature.

explanation:

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.