Answer:
25 m/s
Explanation:
F=ma
15 N =(3 kg)a
a = 5 m/s^2
change in velocity = a*t = (5 m/s^2) * (5 secs) = 25 m/s
Answer:
Gravitational force between masses there is Gravitational force .
Answer:
c. nine times as low.
Explanation:
Sound intensity is defined as the acoustic power transferred by a sound wave per unit of normal area to the direction of propagation:
Since the sound wave has a spherical wavefront of radius r, then the area is given by:
Here r is the distance from the source of the sound. Thus sound intensity decreases as:
Answer:
the time taken for the motion is 3.37 s
Explanation:
Given;
initial velocity of the skydiver, u = 0
final velocity of the skydiver, v = 33 m/s
The time taken for the motion is calculated as;
v = u + gt
33 = 0 + 9.8t
33 = 9.8t
t = 33 / 9.8
t = 3.37 s
Therefore, the time taken for the motion is 3.37 s
8) the energy released by fusion is generally 3 to 4 times larger than with fission. Fission has very few by-products but fusion releases large amounts of radioactive particles because it starts with large nuclei.
9) Alpha particles are 2 protons and 2 neutrons all put together. It's really the nucleus of a helium atom. It is most dangerous if you ingest it but it can be stopped with a sheet of paper so outside the body it's not as dangerous as others and due to its size it can't get very far in the air before hitting air molecules
beta particles are high energy electrons or positrons. They travel further due to their small size but can be stopped by a thin barrier of plastic or wood.
Gamma rays are high frequency photons (light) They are stopped by metal plates and go through human tissue. They are quite dangerous.
10) The mass that is lost in chemical reactions is very small. Solve E=mc² for mass and you get m=E/c². This says the mass you lose is equal to the energy you gained divided by the speed of light squared. c² is a VERY big number so you need a lot of energy produced to notice it. Chemical reactions are simply too inefficient to get that much energy out.
11)You need high temperatures for fusion because you're trying to push two atoms together (to "fuse" them as the name suggests) The electrons in one atom repel the other electrons in the other atoms. When stripped down to only protons, you still have to overcome this repulsion (Coulomb repulsion). High temperatures means high velocity of the particles in the plasma. This gives them enough "oomph" to get close enough to fuse. Once close enough to each other, the nuclear force takes over and overwhelms the Coulomb repulsion and the nuclei fuse and release energy in doing so.
