I I throw a baseball across an open field, at what part of its path does the bal
ID: 2303931 • Letter: I
Question
I I throw a baseball across an open field, at what part of its path does the ball have a minimum speed? A. Right before it hits the ground. B. Right after it leaves my hand. C. Halfway to the top of its path. D. At the top of its path. E. There is not enough information to say. 30. If the intensity of a sound is increased by a factor of 100, how is the decibel level changed? The new decibel level will be A. two units greater B. double the old one C. twenty units greater D. ten times greater E. one half the old one 31. Mass and which other two quantities make up the three basie quantities in mechanics used by physicists to derive additional quantities? A. length and time B. velocity and acceleration C. length and force D. power and force E. force and time 32. If the momentum of a single object is tripled, its kinetic energy will change by what multiplicative factor? A. one-third B. three C. nine D. six E. zero 33. According to Newton's second law, the angular acceleration experienced by an object is directly proportional to which of the following? A. the object's center of mass B. the net applied torque and its moment of intertia C. its moment of inertia D. the object's size E. the net applied torqueExplanation / Answer
29.D. A projectile will have a minimum speed at the top of its path. At this point the vertical velocity will be zero hence no vertical component of velocity.
30.B. Since the relation I'/I= 10log(new intensity/old intensity) = I'/I = 10log(100I/I) . Therefore double the old one.
31.A. Mass, length and time are the three basic quantities in mehanics.
32.C. Relation between Kinetic energy and momentum is given by KE = (1/2)P2/m where P is the momentum. There is P is tripled KE will become 9 times.
33.E. Torque = I x alpha where I is moment of inertia. Therefore angular acceleration is directly proportional to the net applied torque.
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