Change in Momentum and Impulse AP Physics C Mechanics MCQ – Exam Style Questions etc.
Change in Momentum and Impulse AP Physics C Mechanics MCQ
Unit 4: Linear Momentum
Weightage : 15-25%
Question
A 300 g cart with a force sensor attached starts at rest on a track. The force sensor exerts a force on the cart to speed it up. The graph above shows the force F exerted by the sensor on the cart as a function of time t. The change in the cart’s momentum during the time interval shown is most nearly
(A) 4.0 N .s
(B) 8.5 N .s
(C) 13 N. s
(D) 25 N .s
(E) 30 N .s
Answer/Explanation
Ans:B
Question
The net force F acting on an object that moves along a straight line is given as a function of time t by \(F (t ) = kt^2 + τ\) , where \( κ = 1 N /s^2\) and τ = 1 N . What is the change in momentum of the object from t = 0 s to t = 3 s?
(A) 6 kg.m/s
(B) 10 kg.m/s
(C) 12 kg.m/s
(D) 30 kg.m/s
(E) It cannot be determined without knowing the initial momentum of the object.
Answer/Explanation
Ans:C
Integrating the equation for the net force and substituting
Question
A block of mass m is pulled by a rope along a horizontal surface with negligible friction. For time t > 0, the magnitude of the acceleration of the object as a function of time is given by the equation a = Ae-kt , where A and k are positive constants. Which of the following expressions determines the impulse exerted on the block by the rope during the time interval 0 < t < t1 ?
A \(A\int ^{t_{1}}_{0}e^{-kt}dt\)
B \(mA\frac{\mathrm{d} }{\mathrm{d} t}[e^{-kt}]_{t_{1}}\)
C \(A\frac{\mathrm{d} }{\mathrm{d} t}[e^{-kt}]_{t_{1}}\)
D \(mAt_{1}[e^{-kt}]\)
E \(mA\int ^{t_{1}}_{0}e^{-kt}dt\)
Answer/Explanation
Ans:E