<span>1.0 cm = 10. N ± 1 N.</span>
Complete Question
An athlete at the gym holds a 3.0 kg steel ball in his hand. His arm is 70 cm long and has a mass of 4.0 kg. Assume, a bit unrealistically, that the athlete's arm is uniform.
What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor? Include the torque due to the steel ball, as well as the torque due to the arm's weight.
Answer:
The torque is ![\tau = 34.3 \ N\cdot m](https://tex.z-dn.net/?f=%5Ctau%20%3D%2034.3%20%5C%20%20N%5Ccdot%20m)
Explanation:
From the question we are told that
The mass of the steel ball is ![m = 3.0 \ kg](https://tex.z-dn.net/?f=m%20%20%3D%20%203.0%20%5C%20%20kg)
The length of arm is ![l = 70 \ cm = 0.7 \ m](https://tex.z-dn.net/?f=l%20%3D%20%2070%20%5C%20cm%20%20%3D%200.7%20%5C%20%20m)
The mass of the arm is ![m_a = 4.0 \ kg](https://tex.z-dn.net/?f=m_a%20%20%3D%204.0%20%5C%20%20kg)
Given that the arm of the athlete is uniform them the distance from the shoulder to the center of gravity of the arm is mathematically represented as
![r = \frac{l}{2}](https://tex.z-dn.net/?f=r%20%3D%20%5Cfrac%7Bl%7D%7B2%7D)
=>
=>
Generally the magnitude of torque about the athlete shoulder is mathematically represented as
![\tau = m_a * g * r + m * g * L](https://tex.z-dn.net/?f=%5Ctau%20%3D%20%20m_a%20%2A%20g%20%2A%20r%20%20%2B%20m%20%2A%20g%20%2A%20%20L)
=> ![\tau = 4 * 9.8 * 0.35 + 3 * 9.8 * 0.70](https://tex.z-dn.net/?f=%5Ctau%20%3D%20%204%20%2A%209.8%20%2A%200.35%20%2B%203%20%2A%209.8%20%2A%20%200.70)
=> ![\tau = 34.3 \ N\cdot m](https://tex.z-dn.net/?f=%5Ctau%20%3D%2034.3%20%5C%20%20N%5Ccdot%20m)
Answer:
The fireman will continue to descend, but with a constant speed.
Explanation:
In kinetic friction <em>(which is the case discussed here) </em>since the fireman is already in motion because of a certain force, once the frictional force matches the normal force, the fireman will stop accelerating and continue moving at a constant rate with the original speed he had. We will need a force greater than the normal force acting on the fireman to cause a deceleration.
We need to understand the difference between static friction and kinetic friction.
Static friction occurs in objects that are stationary, while kinetic friction occurs in objects that are already in motion.
In static friction, when the frictional force matches the weight or normal force of the object, the object remains stationary.
While in kinetic friction, when the frictional force matches the normal force, the object will stop accelerating. This is the case of the fireman sliding down the pole as discussed above.
Answer:
None.
Explanation:
Molecules are formed by an element's need or excess of electrons. For example, in nature oxygen generally exists as 02. Other molecules are formed via chemical reaction. The example here is the burning of gasoline. Gasoline's two main byproducts are water and carbon dioxide.
Hydrogen as an atom has one electron making it unstable. Put a second hydrogen atom next to the first and the two atoms will share electrons to fill the first energy level the atom needs to be stable.