Physics is Life

A rigid body with moment of inertia 0.8 kg m2 rotates with constant angular velocity about a fixed axis. It has a rotational kinetic energy 2.9 J. Find the magnitude of the angular momentum of the object.

Two children masses 37.9 kg and 39.8 kg are sitting at different points on the edge of a rotating merry-go-round with radius 4.2. What is the moment of inertia for the two children?

A laser beam coming from the Earth is directed towards the moon. The beam diverges at an angle of 0.0007933. If the distance between the moon and the Earth is 384,400km, what is the diameter of the spot that the beam makes on the moon?

A 1,381 kg station wagon is moving along a straight highway at 11.09 m/s. Another car with mass 1,724 kg and speed 23.7 m/s, has its center of mass 36.09 m ahead of the center of mass of the station wagon. Find the position of the center of mass of the system consisting of the two vehicles.

A uniform disk with mass 53.07 kg and radius 345 cm is pivoted at its center about a horizontal, frictionless axle that is stationary. The disk is initially at rest then a constant force of 25.39 N is applied tangent to the rim of the disk. What is the magnitude of the linear velocity v of a point on the rim of the disk after the disk has turned through 0.4314 revolutions?

A bicycle wheel has an initial angular velocity of 2.461 rad/s. If its angular acceleration is constant and equal to 0.2224 rad/s2 , what is its angular velocity at time 2.605 sec?

An amusement park ride has a diameter of 14 meters and revolves at 10 revolutions per minute. What is the linear velocity of a rider sitting at the outermost part of the ride?

A wheel of radius 3.33 m is spinning with a constant angular velocity of 4.41 rad/s. What is the centripetal acceleration of a point on the wheel's rim?

An old music record rotates at 32.62 revolutions per minute. What is its angular speed in radians per second?

How we did the Experiment:

1. Using 2 spring balance, pull the opposite sides of the arm balance to create an equilibrium system

that orients the balance horizontally.

2. Based on the reading on forces, position and angles, determine the summation of torques created

by these 2 forces. The resulting summation serves as the experimental value.

3. The theoretical value for the summation of forces is obviously zero. Thus, zero is the theoretical

value for the summation of forces.

4. Make another 4 trials by changing the forces, position and angles of the two spring balances.

5. Determine the average value of the experimental torque and the theoretical torque in each trial.

Question:

Which do you think will assume a near zero percent difference for the summation of torques in this system, forces applied in greater magnitude or forces applied in smaller magnitude? Explain.

Which do you think will assume a near zero percent difference for the summation of torques

in this system, forces applied in greater magnitude or forces applied in smaller magnitude?

Explain.

What are the factors contributing to the difference between the torques created at the left

arm and the torque created at the right arm if theoretically the value of the summed up

torques is supposed to be zero?

In the applied force caused by the pulling spring scale, it is obvious that there is a

component of this force with respect to the horizontal. What compensates to this horizontal

force in the equilibrium system? Why did the system not move horizontally?

A force of 841.3 N stretches a certain spring a distance of 0.2458 m. What is the potential energy stored in the same spring if it was compressed 0.0325 m?

A 1,570 kg sports car is moving west at 55.01 m/s on a level road when it collides with a 3,839 kg truck driving east on the same road at 29.15 m/s. The two vehicles remain locked together after the collision. What is the velocity of the two vehicles after the collision?

An 1,514 kg car is travelling at 26.57 m/s. How fast should an 4,813 kg truck be moving to have the same momentum as the car?

A 1.509 kg golf ball that is initially at rest is given a speed 29.39 m/s when a club strikes it. If the club and the are in contact for 0.0029 seconds, what average force (in kN) acts on the golf ball?