Physics Answers

1. The angular velocity of a rotating wheel increases by 1.6rev/s every minute. The angular acceleration in rad/s^2 of this wheel is: 
2. A Ping-Pong ball is shot into a circular tube that is lying flat (horizontal) on a tabletop. When the Ping-Pong ball exits the tube, which path will it follow in Figure below?
3. A crane has an arm length of 8.1 m inclined at 30^o with the vertical. It carries a container of mass of 2.6 kg suspended from the top end of the arm. Find the magnitude of the torque produced by the gravitational force on the container about the point where the arm is fixed to the crane. (Neglect the weight of the arm)

1. A ball of mass m1=0.39kg moving east (+x direction) with a speed of 5m/s collided head on with ball m2 with mass 0.27kg ball which is at rest. If the collision is perfectly Elastic, what will be the speed of the ball m1 after the collision?
2. A sled with a mass of 24.8kg rests on a horizontal sheet of essentially frictionless ice. It is attached by a 6.9−m rope to a post set in the ice. Once given a push, the sled revolves uniformly in a circle around the post. If the sled makes five complete revolutions every minute, find the force F exerted on it by the rope.
3. A car of mass 831-kg, as shown in the figure below, is pushed along a floor with a force of 478.4-N for a distance of 8.9-m. Calculate the work done.

Read the statements carefully and underline the word or group of words that makes the statement incorrect then change it to make it correct. 13. Momentum is the product of the force and the time the force is applied on the body. The change in momentum is equal to impulse, or Ft= mΔv. 14. The law of conservation of momentum states that the total momentum of a system before collision is equal to the total momentum of the system after collision. 15. For perfectly elastic collisions, the total energy of the system remains the same.

TRUE or FALSE.

Inverse square law states that sound intensity is directly proportional to the square of the distance between the source and the listener.

Read the statements carefully and underline the word or group of words that makes the statement incorrect then change it to make it correct. 7. For perfectly elastic collisions, the total KE of the system remains the same before and after collision. 8. For inelastic collisions, the total KE before collision is not equal to the total KE after collision. 9. The coefficient of restitution is the ratio of the relative velocities of the bodies after collision to the relative velocities of the bodies before collision. 10. In a perfectly inelastic collision, the total energy before and after collision is the same, while in an inelastic collision, the total energy before collision is not the same as the total energy after collision. 11. Motion of particles can be predicted using the laws of conservation of momentum and laws of conservation of mechanical energy. 12. Impulse is the product of the mass and the velocity of an object. The change in momentum is Δp= mΔv.

TRUE or FALSE.

The sound intensity produced by a given sound source is directly proportional to the square of the distance from the source.

consider a block of wood that floats with 60 percent of its volume above water. (The volume of block is 0.5 m³.) 16. What is the density of the block of wood if the density water is 1000 kg/m³? A. 40 kg/m³ B. 400 kg/m³ C. 60 kg/m³ D. 600 kg/m³ 17. What is its mass? A. 200 kg B. 300 kg C. 400 kg D. 600 kg 18. What volume of water did the block of wood displace? A. 0.1 m³ B. 0.2 m³ C. 0.3 m³ D. 0.5 m³ 19. What is the buoyant force of water on the block of wood? A. 1960 N B. 2940 N C. 3920 N D. 4900 N 20. Suppose this block of wood is placed in a liquid of density 500 kg/m³. What will happen to the block of wood? A. It will sink. B. It will be partially submerged. C. It will float with no part of it above the surface of liquid. D. All of these are possible.

You hang your picture frame by means of a vertical string. Two strings in turn support this string, as shown in the figure. Each string makes 30˚ with an overhead horizontal beam. Find the tension in the strings if the weight of the frame is 55 N

3. A 5kg block is connected to a 3kg block by means of a string that passes over a pulley. Find the (a) unbalanced force, (b) acceleration of the blocks, and (c) tension in the string. Assume that the pulley and the surfaces are frictionless.

Hearing is very important, so you need to take good care of your ears. Avoid loud sounds, which could hurt your ears and cause hearing damage. Expound this idea using Physics concepts.