On your way home after the final exam, you open a 12-kg door that is 1 m wide, a
ID: 1410415 • Letter: O
Question
On your way home after the final exam, you open a 12-kg door that is 1 m wide, applying a constant force of 40 N in a direction perpendicular to the vector pointing from the hinges to the place where the force is applied. If you push on the door at a distance 0.90 m from the hinges, what is the door’s angular acceleration, and what is the torque on the door? The moment of inertia of a thin rectangle rotating about one end is (1/3) M L2.
Which of the following is neither given nor readily determined _____ from the given information?
a) The mass of the door
b) The force exerted on the door
c) The distance from the hinges to the applied force
d) The angular acceleration of the door
e) The moment of inertia of the door.
19. Which of the following concepts or principles best apply to _____ finding the final velocity of the heavier ball?
a) Conservation of energy
b) Newton’s second law in rotational form
c) Newton’s second law in translational form
d) Uniform circular motion
e) Newton’s second law in translational form
20. What is the magnitude of the torque exerted on the door? _____
a) 36 kg m N
b) 6 m N
c) 10.8 m N
d) zero
e) 480 m N
21. What is the moment of inertia of the door? _____
a) 3.2 kg m2
b) 4 kg m2
c) 12 kg m2
d) 39.2 kg m2 rightward
22. What is the angular acceleration of the door? _____
a) 3.0 rad/s2
b) 1.5 rad/s2
c) 9.0 rad/s2
d) 120 rad/s2
e) zero
Explanation / Answer
d) The angular acceleration of the door
b) the torque done is
= R F = 0.90 m * 40 N = 36 N.m
a) the angular acceleration is
= I ---> = / I
where
I = ( M L2 ) / 3 = ( 12 Kg * (1 m)2 ) / 3 = 4 Kg.m
hence
= ( 36 N.m ) / ( 4 Kg.m ) = 9 rad/s2
19.- b) Newton's second law in rotational form
20.- a) 36 kg m N
21.- b) 4 kg m2
22.- c) 9.0 rad/s2
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.