Answer:
(d) a net external force must be acting on the system
Explanation:
Momentum is given as the product of mass and velocity.
P = MV
According to Newton's second law of motion, " Force applied to a body (system) is directly proportional to the rate of change of momentum of the body (system) which takes place in the direction of the applied force (external force).
F ∝ΔMV
Therefore, If the total momentum of a system is changing, a net external force must be acting on the system.
(d) a net external force must be acting on the system
Hi. The answer is, "gram". Hope this helps.
Take care,
Diana
Answer:
n = 223 revolutions
Explanation:
It is given that,
The angular acceleration of a helicopter blade,
Initial speed of the helicopter blade,
The final speed of the blade,
We need to find the number of revolutions. Firstly we will find the angle turned by the blade. Let the angle is . So,
Let there are n number of revolutions made by the blade. So,
or
n = 223 rev
So, there are 223 revolutions.
KE= 0.5(m)(v^2)
KE= 250,000 J
<span>Frequency of the pendulum F = 0.15Hz
Acceleration due to gravity g = 9.81 m/s^2
Period of the pendulum is calculated by T = 2 x 3.14 x squareroot of (L / g), L being the length of the pendulam.
We have an equation between T and F => T = 1 / F
T = 1 / 0.15 => T = 20 / 3
Now substituting the values
=> 20 / 3 = 2 x 3.14 x squareroot of (L / 9.81)
=> 3.33 = 3.14 x squareroot of (L / 9.81)
=> squareroot of (L / 9.81) = 3.33 / 3.14
=> L / 9.81 = 1.06^2
=> L = 1.13 x 9.81
Length of the pendulum = 11 m</span>