Answer:
False
Explanation:
Energy keeps on converting from one form to another and it is useful in each of its forms.
For instance, the kinetic energy get converts into potential energy, mechanical energy of motor converts into electrical energy, sound energy (phone) converts into electrical energy etc. but in all these forms energy is useful in one or the other way.
Hence, the given statement is false.
Answer:
v₂ = 1.8 [m/s]
Explanation:
To be able to solve this problem we must raise the principle of conservation and quantity of movement. It is going to study the momentum before and after the firing of the rifle.
P = m*v
where:
P = momentum [kg*m/s]
m = mass [kg]
v = velocity [m/s]
Now we need to analyze the moment before and after the shot.
where:
m₁ = mass of the rifle = 5 [kg]
v₁ = velocity of the rifle and the bullet before firing = 0 (no movement)
m₂ = mass of the bullet = 15 [g] = 0.015 [kg]
v₂ = velocity of recoil [m/s]
v₃ = velocity of the bullet after firing = 600 [m/s]
Now replacing:
Answer:
Increase in speed.
Explanation: Since mass must be conserved, if the cross section of the flow tube is not the same, that is varies, the flow speed must change to conserve mass.
This means that there is a non-zero net force acting on the fluid that causes the fluid to increase or decrease in speed depending on whether the fluid is flowing through a portion of the tube with a smaller or larger cross
Answer:
R₂ = 3.31 m
Explanation:
For this exercise let's use trigonometry. Let's see the angle of the full moon
θ = x / R
Where x is the diameter of the moon and R the distance from the Earth to the Moon, the angle is measured in radians
x = 2 R
x = 2 1.74 10⁶
x = 3.48 10⁶ m
The distance is
R = 3.84 10⁸ m
Let's look for the supported angle
θ = 3.48 10⁶ / 3.84 10⁸
θ = 9.06 10⁻³ rad
For the coin to cover the moon it must have the same angle, let's look for the different
θ = x₂ / R₂
x₂ = 3 cm = 0.03 m
R₂ = x2 / θ
R₂ = 0.03 / 9.06 10⁻³
R₂ = 3.31 m
This distance in much greater than the arm length