Work AP Physics 1 MCQ – Exam Style Questions etc.
WORK AP Physics 1 MCQ
Unit: 3. Work , Energy and Power
Weightage : 10-15%
Exam Style Practice Questions, Work AP Physics 1 MCQ
Question
For a particular nonlinear spring, the relationship between the magnitude of the applied force F and the resultant displacement x from equilibrium is given by the equation \(F = kx^2\). What is the amount of work done by stretching the spring a distance \x_o\)?
(A)\(kx^3_0\)
(B)\(\frac{1}{3}kx_0\)
(C)\(\frac{1}{2}kx^2_{0}\)
(D)\(\frac{1}{3}kx^2_{0}\)
(E)\(\frac{1}{2}kx^3_0\)
Answer/Explanation
Ans:E
Question
In the lab setup above, block 1 is being pulled across a smooth surface by a light string connected across a pulley to a falling block 2. The pulley has negligible mass and friction. Students measure the mass of each block, the distance from A to B, and the speeds of the block on the surface at points A and B. Which of the following hypotheses can be tested with this setup?
A As block 1 moves from point A to point B , the work done by the tension on block 1 is equal to the kinetic energy of block 1 at point B .
B As block 1 moves from point A to point B , the work done by the tension on block 1 is equal to the kinetic energy of the two-block system when block 1 is at point B .
C As block 1 moves from point A to point B , the work done by gravity on block 2 is equal to the kinetic energy of block 1 at point B .
D As block 1 moves from point A to point B , the work done by gravity on block 2 is equal to the change in the kinetic energy of the two-block system.
E As block 1 moves from point A to point B, the work done by the tension on block 2 is equal to the kinetic energy of block 2 when block 1 has reached point B .
Answer/Explanation
Ans:D
The work done by gravity on block 2 will move the two blocks and be equal to the change in kinetic energy of the two-block system.Question
In an experiment, a variable, position-dependent force F(x) is exerted on a block of mass 1.0kg that is moving on a horizontal surface. The frictional force between the block and the surface has a constant magnitude of Ff. In addition to the final velocity of the block, which of the following information would students need to test the hypothesis that the work done by the net force on the block is equal to the change in kinetic energy of the block as the block moves from x=0 to x=5m ?
A The function F(x) for 0<x<5 and the value of \(F_f\).
B The function a(t) for the time interval of travel and the value of \(F_f\).
C The function F(x) for 0<x<5, the block’s initial velocity, and the value of \(F_f\).
D The function a(t) for the time interval of travel, the time it takes the block to move 5 m, and the value of \(F_f\).
E The block’s initial velocity, the time it takes the block to move 5 m , and the value of \(F_f\).
Answer/Explanation
Ans:C
Using the function F(x) and the value of \(F_f\), the work done by the net force in moving the block from x=0 to x=5m can be calculated. Using the mass and initial and final velocities, the change in kinetic energy can be calculated; thus, the hypothesis that the work done is equal to the change in kinetic energy can be testedQuestion
A 2kg block is sliding up a surface inclined at an angle of 30° above the horizontal. The block has the speeds indicated in the figure when it passes points L and K. The distance between points L and K is 2m . Which of the following includes a correct claim about the interaction of the block and the surface with supporting evidence from the figure?
A The surface is rough, because the work-energy theorem indicates the block should be traveling faster at point K .
B The surface is rough, because the work-energy theorem indicates the block should be traveling slower at point K .
C The surface is smooth, because the work-energy theorem indicates the block should be traveling faster at point K .
D The surface is smooth, because the work-energy theorem indicates the block should be traveling with the indicated speed at point K .
E The surface is smooth, because the work-energy theorem indicates the block should be traveling slower at point K.
Answer/Explanation
Ans:A
Using the work-energy theorem, the speed at point K would be \(U_1+K_1=U_2+K_2\)\(0+\frac{1}{2}m(v_{1})^2=mgh_2+\frac{1}{2}m(v_{2})^2\)
\(v_2=\sqrt{v_1^2-2gh_2}=\sqrt{\left ( 7\frac{m}{s^2} \right )^2-2\left ( 10\frac{m}{s^2} \right )(2m)(sin30)}\)
\(v_2=5.4m/s\) . Since the actual speed at point K is slower than this value, there must have been friction between the block and surface.
Question
A 2 kg block is initially at rest on a horizontal frictionless table. A force of 15 N is then exerted on the block at an angle of 37 degrees to the horizontal, as shown below.
The figure shows a block on a table. The block is labeled 2 k g. There is an arrow pointing down and to the right that meets the top left corner of the block. The arrow makes an angle of 37 degrees below the horizontal. The arrow is labeled 15 N.
The change in the kinetic energy of the block after moving a distance of 3 m is most nearly
A 60 J
B 45 J
C 36 J
D 27 J
E 24 J
Answer/Explanation
Ans:C