Answer:
The answer to your question: d.
Explanation:
a. The rate of change of momentum of an object is equal to the net force applied to the object.
This is the second a law of motion, so this answer is incorrect.
b. In the absence of a net force acting on it, an object moves with constant velocity.
This is the first Newton law of motion, so this option is not correct.
c. For any force, there always is an equal and opposite reaction force.
This is the third law of motion, so this is not the right option.
d. What goes up must come down.
Newton said this sentence, but is not part of the law of motion.
<span>In a rocket combustion chamber the rocket exhaust is forced out of the nozzle by the rapid expansion of exhaust gases and the directing shape of the rocket nozzle. The equal and opposite reaction is that the rocket nozzle (and hence the shuttle it is attached to) is forced in the other direction</span>
Flower pollen on water or smoke in a glass box.
<span>Both show random motions of the flower pollen and smoke due to the random motion of the water and air molecules.</span><span>Jan Ingenhousz had described the irregular motion of coal dust particles on the surface of alcohol in 1785. Nevertheless Brownian motion is traditionally regarded as discovered by the botanist Robert Brown in 1827. It is believed that Brown was studying pollen particles floating in water under the microscope. He then observed minute particles within the vacuoles of the pollen grains executing a jittery motion. By repeating the experiment with particles of dust, he was able to rule out that the motion was due to pollen particles being 'alive', although the origin of the motion was yet to be explained. Consider a large balloon of 10 meters in diameter. Imagine this large balloon in a football stadium or any widely crowded area. The balloon is so large that it lies on top of many members of the crowd. Because they are excited, these fans hit the balloon at different times and in different directions with the motions being completely random. In the end, the balloon is pushed in random directions, so it should not move on average. Consider now the force exerted at a certain time. We might have 20 supporters pushing right, and 21 other supporters pushing left, where each supporter is exerting equivalent amounts of force. In this case, the forces exerted from the left side and the right side are imbalanced in favor of the left side; the balloon will move slightly to the left. This imbalance exists at all times, and it causes random motion. If we look at this situation from above, so that we cannot see the supporters, we see the large balloon as a small object animated by erratic movement. Now return to Brown’s pollen particle swimming randomly in water. One molecule of water is about .1 to .2 nm, (a hydrogen-bonded cluster of 300 atoms has a diameter of approximately 3 nm) where the pollen particle is roughly 1 micrometer in diameter, roughly 10,000 times larger than a water molecule. So, the pollen particle can be considered as a very large balloon constantly being pushed by water molecules. The Brownian motion of particles in a liquid is due to the instantaneous imbalance in the force exerted by the small liquid molecules on the particle. Okay, I hope that'll answer your question!
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Answer:
The coefficient of kinetic friction between the block and the surface is 0.127.
Explanation:
Given that,
The mass of a block, m = 4 kg
The acceleration of the block, a = -1.25 m/s²
We need to find the coefficient of kinetic friction between the block and the surface. The force of friction is given by :
So, the coefficient of kinetic friction between the block and the surface is 0.127.
<h3>The wavelength corresponds to the lower cut-off point of the sounds is 22.93 meter</h3>
<em><u>Solution:</u></em>
Given that,
A dog can hear sounds in the range from 15 to 50,000 Hz
The speed of sound at a temperature of 
is: 344 m/s
To find: wavelength
Where,
v is speed of sound
f is the frequency
f = lower cut off point = 15 Hz
Thus the wavelength corresponds to the lower cut-off point of the sounds is 22.93 meter
