multiple choice physics question Neglect air resistance in ALL problems, let 9=1
ID: 1351298 • Letter: M
Question
multiple choice physics question Neglect air resistance in ALL problems, let 9=10m/s2 if section: needed. DO FRICTION UNLESS TOLD TO (or if not applicable) Block A sits on block B. A constant force is applied to block B, causing it to accelerate to the right. Block A rides on block B without slipping. What must be true? [2 pts] a) Block B exerts a friction force on Block A, directed to the left b) Block B exerts a friction force on Block A, directed to the right c) Block B does not exert a friction force on Block A d) There is no net force on block A 2) consider the following overhead views of particles on a string in constant horizontal circular motion. All 4 particles are moving with the same speed. What is the correct ranking of tensions (smallest to largest) in the strings?[2 pts]Explanation / Answer
(1)
The correct option is ( b)
As you apply a force toward right, the block A gets backward jerk. In this case, the frictional force due to block B oppose the backward motion of block A, which acts towards right.
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(2)
In this case, tension in string is equal to centripetal force acting on particle
T = m v2/ r
In figure 1: T = m v2/ r
Figure 2: m v2/ 2 r = 0.5 ( m v2/ r )
Figure 3: 2m v2/ r = 2 ( m v2/ r )
Figure 4: 2m v2/ 2 r = m v2/ r
Thus, the raking of tensions from greatest to smallest
T3 > T1= T4 > T2
Thus the correct option is ( a )
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