Mort stands on Earth. Velma moves away from him in a rocket, at 299,000 km/s (1000 km/s slower than lightspeed). Mort sends a laser beam toward Velma. As the tip of the beam passes her rocket, Velma observes that
A) the laser beam moves past her at just 1000 km/s.
B) the laser beam moves past her at 300,000 km/s.
C) Both of the above.
D) the laser beam never catches up with her.
E) Mort has turned into a giant frog.
B
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A child is riding a tricycle. The pedals are attached directly to the front wheel, which has a radius of 13 cm. The rear wheels are smaller, and have a radius of 8.0 cm
If the child is pedaling at 16 rpm, what is the angular speed of the rear wheels? A) 15 rpm B) 26 rpm C) 24 rpm D) 20 rpm E) 50 rpm
Plane waves of ultrasound, f = 51.0 kHz, impinge on a flat plane with a 1.00-cm-wide slit. What is the total angular width (2?) of diffracted sound waves when the speed of sound in air is 340 m/s
a. 167° b. 83.6° c. 19.5° d. 41.8° e. 0.11°
Olbers's paradox seeks the explanation for why the night sky is dark
Indicate whether the statement is true or false
You are on a boat in a fog and know there are cliffs ahead of you somewhere, but you cannot see them. You use your fog horn to send out a blast of sound (assume the temperature of the air is 20 oC) and the time it takes for the sound to return to you is 20.0 s. How far away are the cliffs (in metric units)? Hint: Be careful and think about the physics of the problem. You may want to make a sketch
of the situation to help you determine the answer. a. 1798 m b. 3444 m c. 3596 m d. 7192 m