Answer:
Explanation:
according to third equation of motion
2as=vf²-vi²
vf²=2as+vi²
vf=√2as+vi²
vf=√2as+vi
vf=√2*2*4+3
vf=√16+3
vf=4+3=7
so final velocity is 7 m/s
Solution:
We have,
Power [P] = 25000 Watt
Mass [m] = 6000 kg
Height [h] = 20 metres
Time [t] = ?
Now,
P = W/t = F x d/t = mxgx h/t
Or, 25000 = 6000 x 10 x 20/25000 [.......g = 10
m/s^2]
Or, t = 6000 x 10 x 20/25000
Or, t = 1200/25
Therefore, t = 48 second
Hence, the required time for the crane to lift the load is 48 seconds.
Answer:
reflection is the act of reflecting or the state of being reflected while echo is
reflection of sound waves from a surface back to the initial listener
Beats are generated by two interfering waves when they have slightly different frequencies.
As the bright sun shines upon the water, the water slowly dissapears. This is an example of physical change because here the water is just transformed into water vapour. So only the state and the shape of the substance has changed. Its originality remains absolutely intact. In the second case where the same sunlight gives energy to the surrounding plants to convert water and carbon dioxide into sugar and oxygen gas, it is a chemical change. here new substances are formed and the identity of the original substances are lost.In chemical reactions, the mass of the product will always be the same as the mass of the reactants.
