Suppose you start with 1 kilogram of a radioactive substance that has a half-life of 10 years. Which of the following statements will be true after 20 years pass?
A) All the material will have completely decayed.
B) You'll have 0.75 kilogram of the radioactive substance remaining.
C) You'll have 0.25 kilogram of the radioactive substance remaining.
D) You'll have 0.5 kilogram of the radioactive substance remaining.
C
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The law of conservation of momentum applies to a collision between two bodies since
a. they exert equal and opposite forces on each other. b. they exert forces on each other respectively proportional to their masses. c. they exert forces on each other respectively proportional to their velocities. d. they exert forces on each other respectively inversely proportional to their masses. e. their accelerations are proportional to their masses.
A circular coil of radius 5.0 cm and resistance 0.20 ? is placed in a uniform magnetic field perpendicular to the plane of the coil
The magnitude of the field changes with time according to B = 0.50e-20t T. What is the magnitude of the current induced in the coil at the time t = 2.0 s? A) 1.3 mA B) 9.2 mA C) 7.5 mA D) 4.2 mA E) 2.6 mA
A space station out beyond the solar system is rotating with constant angular velocity. A spaceship heading into the station along a diameter of the station, uses its rockets to brake, and then docks inside the station at its center. When the spaceship docks, the angular momentum of the system consisting of the station and ship
a. is less than the original angular momentum of the station. b. is the same as the original angular momentum of the station. c. is greater than the original angular momentum of the station. d. is less than the original angular momentum of the station, but the angular velocity increases. e. is greater than the original angular momentum of the station, but the angular velocity decreases.
A mass of 0.40 kg, hanging from a spring with a spring constant of 160 N/m, is set into an up-and-down simple harmonic motion. What is the speed of the mass when moving through a point at 0.05 m displacement? The starting displacement of the mass is 0.10 m from its equilibrium position
a. zero c. 1.7 m/s b. 1.4 m/s d. 1.2 m/s