If one lawn mower causes an 80-dB sound level at a nearby point, what sound level at that point would four lawnmowers together cause?
86 dB
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Experienced players can throw a Frisbee so it skips off the ground (the Frisbee’s front edge actually tips upward after the Frisbee hits, enabling it to climb back into the air). If a right-handed player throws a Frisbee in the usual way, it rotates counterclockwise when viewed from above. To skip the Frisbee, which edge has to hit the ground (as seen by the thrower)? (Hint: The Frisbee’s angular momentum vector, and thus its rotation axis, changes in the direction of the external torque that the strike applies to the Frisbee.)
A. The back edge B. The front edge C. The right edge D. The left edge E. The entire rim must hit the ground simultaneously.
An iron ball and a wooden ball of the same size are dropped from a tall tower. Taking air resistance into consideration, the object to hit the ground first will be the
A) lighter wooden ball. B) heavier iron ball. C) both hit at the same time. D) not enough information
All dark matter in our Universe falls into the category of "hot dark matter"
a. True b. False Indicate whether the statement is true or false
Al is moving by you at a very high speed (close to the speed of light). You get out a clock and measure 10 seconds going by. If you also watch a clock in Al's ship, how much time will you see it record during your 10 seconds?
A) Al's clock will record less than 10 seconds. B) Al's clock will record more than 10 seconds. C) Al's clock will agree that 10 seconds go by.