A skydiver steps from a helicopter and falls for a few seconds until terminal velocity is reached. Thereafter, until he opens his parachute, his acceleration
A) is constant.
B) increases.
C) decreases.
D) is zero.
E) none of the above
Answer: D
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A sewing machine needle moves up and down in simple harmonic motion with an amplitude of 1.27 cm and a frequency of 2.55 Hz. (a) What is the maximum speed of the needle? (b) What is the maximum acceleration of the needle?
What will be an ideal response?
Galaxies seem to be made mostly of dark matter. One type of evidence for this comes from observations of
A) the redshift in the light from the explosions of distant supernovas. B) the redshift in the light from the earliest galaxies in the universe. C) Both of the above. D) the speeds at which gas clouds orbit the centers of galaxies. E) distant quasars.
A 0.25 kg ideal harmonic oscillator has a total mechanical energy of 4.0 J. If the oscillation amplitude is 20.0 cm, what is the oscillation frequency?
A) 4.5 Hz B) 1.4 Hz C) 2.3 Hz D) 3.2 Hz
Consider the curve f(x) = A cos(2?x/?). The wavelength of the wave will be:
a.
the distance 0 to A.
b.
twice the distance 0 to A.
c.
the distance x2 to x3.
d.
twice the distance x2 to x3.