If it starts at rest the initial velocity is 0.
For an acceleration, a, and time, t, the velocity is v=at. Since at t=4, v=7, then a=7/4=1.75m/s^2
You are correct, the answer is C.
Good insulators are materials that do not allow heat, electricity, light or sound pass through easily. Materials like steel and silver (which are metals) are not good insulators because they make good conductors. They easily allow heat, electricity and the like pass through them.
Thus, the answer is letter C. Rubber.
Answer:
The velocity will be v1 = 0.58[m/s]
Explanation:
This problem can be solved by the law of conservation of the moment, which explains that the moment of a system remains constant because there are no external forces acting on it.
We have the following initial data:
m1 = mass of the skater = 55 [kg]
m2 = mass of the ball = 3 [kg]
v2 = velocity of the ball = 8 [m/s]
Therefore:
![m_{1}*v_{1}+m_{2}*v_{2}=m_{1}*v_{1}+m_{2}*v_{2}\\(50*0)+(3*0)=(50*v_{1})+(3*8)\\50+3-24=50*v_{1}\\v_{1}= 0.58[m/s]](https://tex.z-dn.net/?f=m_%7B1%7D%2Av_%7B1%7D%2Bm_%7B2%7D%2Av_%7B2%7D%3Dm_%7B1%7D%2Av_%7B1%7D%2Bm_%7B2%7D%2Av_%7B2%7D%5C%5C%2850%2A0%29%2B%283%2A0%29%3D%2850%2Av_%7B1%7D%29%2B%283%2A8%29%5C%5C50%2B3-24%3D50%2Av_%7B1%7D%5C%5Cv_%7B1%7D%3D%200.58%5Bm%2Fs%5D)
Answer:
the decrease in energy is due to a transformational in internal energy of the body in the rebound.
Explanation:
For this exercise we can calculate the initial and final mechanical energy
Em₀ = U = m g y₁
= U = m g y₂
we look for the variation of the energy
ΔEm = Em_{f} - Em₀
ΔEm = m g (y_{f} -y₀)
ΔEm = m g (0.86 -1.2)
ΔEm = -3.332 m
We can see that there is a decrease in mechanical energy, this is transformed into internal energy of the ball during the impact with the ground, this energy can be formed by several factors such as a part of the friction with the surface, an increase in body temperature or a deformation of the body; there may be a contribution from several of these factors.
In conclusion the decrease in energy is due to a transformational in internal energy of the body in the rebound.
Answer:
The mass of an electron is only about 1/2000 the mass of a proton.
Explanation: