A 10-kg block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block is
A) 1 m/s2.
B) 2 m/s2.
C) 5 m/s2.
D) 10 m/s2.
E) none of the above
Answer: A
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A guitar-like stringed instrument has a string that is 16 cm long. It sounds the musical note A (440 Hz) when played without fingering. By what distance should you shorten it to play the note C (523 Hz)?
A) 1.7 cm B) 3.4 cm C) 2.5 cm D) 4.2 cm
Free Fall: A ball is projected upward at time t = 0 s, from a point on a flat roof 10 m above the ground. The ball rises and then falls with insignificant air resistance, missing the roof, and strikes the ground. The initial velocity of the ball is 58.5 m/s. Consider all quantities as positive in the upward direction. At time t = 5.97 s, the vertical velocity of the ball is closest to
A. 0 m/s. B. +175 m/s. C. +12 m/s. D. -175 m/s. E. -12 m/s.
What is the energy of a photon of wavelength 3 cm?
A) 82 eV B) 4.1 × 10-5 eV C) 41 eV D) 4.1 × 10-5 J E) 3 ergs
Beats: Two taut strings of identical mass per unit length are stretched with the same tension with their ends fixed, but one string is 0.330 cm longer than the other. Waves on these strings propagate at 34.0 m/s.The fundamental frequency of the shorter string is 258 Hz. What is the beat frequency when each string is vibrating at its fundamental frequency?
A. 12.3 Hz B. 9.00 Hz C. 12.0 Hz D. 12.7 Hz E. 11.3 Hz