A spaceship moves away from the Earth with a speed of 0.80c. The spaceship then fires a missile with a speed of 0.50c relative to the spaceship
(a) What is the velocity of the missile measured by observers on the Earth if the missile is fired away from the Earth? (b) What is the velocity of the missile measured by observers on the Earth if the missile is fired toward the Earth?
(a) 0.93c
(b) 0.50c
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A block is placed in oscillation on a frictionless horizontal surface attached to a spring that is also attached to a wall. If, when stretched away from equilibrium by 15 cm and released, it oscillates with a period of 0.25s, and if the mass of the block is 15 kg, what force was required to stretch the spring by the initial 15 cm?
A. 230 N B. 450 N C. 710 N D. 360 N E. 1400 N
Beryl states that insulation with the smallest possible thermal conductivity is best to keep a house warm in winter, but worst for keeping a house cool in summer. Sapphire insists the reverse is true: low thermal conductivity is good in the summer, but bad in the winter. Which one, if either is correct?
A. Beryl, because low thermal conductivity results in low heat transfer. B. Beryl, because low thermal conductivity results in high heat transfer. C. Sapphire, because low thermal conductivity results in low heat transfer. D. Sapphire, because low thermal conductivity results in high heat transfer. E. Neither, because low heat transfer is desirable both in summer and in winter.
A person tries to heat up her bath water by adding 5.0 L of water at 80°C to 60 L of water at 30°C. What is the final temperature of the water?
A) 34°C B) 36°C C) 38°C D) 40°C E) 65°C
A charge of 8.0 pC is distributed uniformly on a spherical surface (radius = 2.0 cm), and a second charge of -3.0 pC is distributed uniformly on a concentric spherical surface (radius = 4.0 cm). Determine the magnitude of the electric field 5.0 cm from the center of the two surfaces
a. 14 N/C b. 11 N/C c. 22 N/C d. 18 N/C e. 40 N/C