Answer:
∑ τ =0, L₀ = 
Explanation:
In a circular turning movement, when the arms are extended and then contracted in two possibilities:
- They are lowered the force of gravity is what pulls them, the tension of the muscle becomes zero to allow this movement.
In this movement the force is vertical(gravity) and the movement of the center of mass of each arm is vertical, so that the work is the weight value of the arm by the distance traveled by the center of mass.
- Another possibility is that the arms have stuck to the body, in this case the person's muscles perform the force, this force is horizontal and the displacement is the horizontal of the center of mass of the arms from the extended position to the contracted
In these movements the torque of the external force is equal for each arm, but in the opposite direction, so they are canceled where a net torque of zero, this causes the angular momentum to be preserved, which changes is the moment of inertia of the system and therefore you must also change the angular velocity to keep your product constant
∑ τ =0
L₀ = 
I₀ w₀ = I w
Answer:
B) The total number of atoms does not change, so mass is conserved in the reaction.
Explanation:
According to the <u><em>Law of Conservation of Mass</em></u>, no matter can ever be created or destroyed. The number of atoms does not change, thus the mass does not change.
Mater doesn't just appear or disappeared. Chemical elements are still there just the connections and how it combines changes.
So what goes into your chemical eqation must still exist after the change.
Acids are danger so stay away
Answer:
20,850 N
Explanation:
We can solve the problem by using second Newton's Law:

where
F is the force
m is the mass
a is the acceleration
In this problem, we have:
m = 70 kg is the mass
is the acceleration (which is negative, because it is a deceleration)
So, we can use the equation above to find the force:

and the negative sign simply means that the force is in the opposite direction to the motion.