If something is going down a hill it can help slow it down
it can stop you from flying off a rollercoaster
Answer:
The force of friction acting on block B is approximately 26.7N. Note: this result does not match any value from your multiple choice list. Please see comment at the end of this answer.
Explanation:
The acting force F=75N pushes block A into acceleration to the left. Through a kinetic friction force, block B also accelerates to the left, however, the maximum of the friction force (which is unknown) makes block B accelerate by 0.5 m/s^2 slower than the block A, hence appearing it to accelerate with 0.5 m/s^2 to the right relative to the block A.
To solve this problem, start with setting up the net force equations for both block A and B:
![F_{Anet} = m_A\cdot a_A = F - F_{fr}\\F_{Bnet} = m_B\cdot a_B = F_{fr}](https://tex.z-dn.net/?f=F_%7BAnet%7D%20%3D%20m_A%5Ccdot%20a_A%20%3D%20F%20-%20F_%7Bfr%7D%5C%5CF_%7BBnet%7D%20%3D%20m_B%5Ccdot%20a_B%20%3D%20F_%7Bfr%7D)
where forces acting to the left are positive and those acting to the right are negative. The friction force F_fr in the first equation is due to A acting on B and in the second equation due to B acting on A. They are opposite in direction but have the same magnitude (Newton's third law). We also know that B accelerates 0.5 slower than A:
![a_B = a_A-0.5 \frac{m}{s^2}](https://tex.z-dn.net/?f=a_B%20%3D%20a_A-0.5%20%5Cfrac%7Bm%7D%7Bs%5E2%7D)
Now we can solve the system of 3 equations for a_A, a_B and finally for F_fr:
![30kg\cdot a_A = 75N - F_{fr}\\24kg\cdot a_B = F_{fr}\\a_B= a_A-0.5 \frac{m}{s^2}\\\implies \\a_A=\frac{87}{54}\frac{m}{s^2},\,\,\,a_B=\frac{10}{9}\frac{m}{s^2}\\F_{fr} = 24kg \cdot \frac{10}{9}\frac{m}{s^2}=\frac{80}{3}kg\frac{m}{s^2}\approx 26.7N](https://tex.z-dn.net/?f=30kg%5Ccdot%20a_A%20%3D%2075N%20-%20F_%7Bfr%7D%5C%5C24kg%5Ccdot%20a_B%20%3D%20F_%7Bfr%7D%5C%5Ca_B%3D%20a_A-0.5%20%5Cfrac%7Bm%7D%7Bs%5E2%7D%5C%5C%5Cimplies%20%5C%5Ca_A%3D%5Cfrac%7B87%7D%7B54%7D%5Cfrac%7Bm%7D%7Bs%5E2%7D%2C%5C%2C%5C%2C%5C%2Ca_B%3D%5Cfrac%7B10%7D%7B9%7D%5Cfrac%7Bm%7D%7Bs%5E2%7D%5C%5CF_%7Bfr%7D%20%3D%2024kg%20%5Ccdot%20%5Cfrac%7B10%7D%7B9%7D%5Cfrac%7Bm%7D%7Bs%5E2%7D%3D%5Cfrac%7B80%7D%7B3%7Dkg%5Cfrac%7Bm%7D%7Bs%5E2%7D%5Capprox%2026.7N)
The force of friction acting on block B is approximately 26.7N.
This answer has been verified by multiple people and is correct for the provided values in your question. I recommend double-checking the text of your question for any typos and letting us know in the comments section.
Answer:
Due to Conservation of Energy just as the ball hits the ground it's potential energy is assumed zero
Therefore disregarding air resistance all energy is converted into potential energy.
So KE = PE
(5 J)
Answer:
0.2289
Explanation:
Power required to climb= Fv where F is force and v is soeed. We know that F= mg hence Power, P= mgv and substituting 700 kg for m, 9.81 for g and 2.5 m/s for v then
P= 700*9.81*2.5=17167.5 W= 17.1675 kW
To express it as a fraction of 75 kw then 17.1675/75=0.2289 or 22.89%
Dark energy is a theoretical repulsive energy that causes the acceleration to the expansion of the universe. Among the choices, the nearest answer would be D. Dark energy can also be defined as a new form of energy, that is a dynamic field that fills up space but has an effect opposite to that of normal energy.