Physics 1/AP C: Rotational Kinematics, Rotational Inertia, Net Torque, Work
A 1 m bar is held horizontally and used to open a crate. The bar is inserted 2 cm into the box and then the other end is pushed down using 20 N of force. What force is exerted on the box lid?
1 000 N
10 000 N
In the scenario above, what was the torque exerted by the bar? (express your answer in kg*m^2)
Newton's first law states that a point particle is in equilibrium if the net forces acting on it are zero. When are torques consdered in Newton's first law?
Torques are never included in Newton's first law.
When the forces are unbalanced.
When considering objects that have dimensions.
Torques are not forces and do not need to be accounted for.
Torques come in pairs and do not need to be accounted for.
Triple the rotational velocity of an object and its rotational kinetic energy will
be nine times as much.
stay the same.
be one third as much.
be one ninth as much.
A propeller starts at rest then rotates about its midpoint with an angular acceleration of 12 rad/s^2. How much time will it take to rotate through π/2?
A cylinder has a moment of inertia, I. How much time does it take a torque, τ, to increase its angular speed from ω1 to ω2?
A barbell consists of a thin rod of uniform mass and two masses at each end. The rod is 0.40 m long and a mass of 0.2 kg. The two masses are each 5 kg. Find the rotational inertia of the barbell if it is rotated halfway between the center of mass and one of the masses.
A body with a moment of inertia of 4 kg*m^2 accelerates constantly from rest with an angular acceleration of 5 rad/s^2. How much time does it take to obtain a rotational kinetic energy of 800 J?
Calculate the net torque on the bar below.
How much work is done on the bar below over 5 seconds?