Mechanics 1
A door is hinged on one side, and a force of 15 N is applied perpendicular to the door at a distance of 0.8 m from the hinge. How much torque is applied by this force to the door?
12 Nm
Two people on ice skates are initially at rest while facing one another. One person has a mass of 60 kg and the other 40 kg. They push off each other and move in opposite directions. If the 60-kg skater moves with a speed of 2.0 m/s, what is the speed of the 40- kg skater, assuming no external forces are acting?
3.0 m/s
An electrical circuit is constructed with a battery and four resistors as shown in the diagram at the right. What is the current measured by the ammeter shown in the diagram?
(Diagram 35)
2 A
Two sound waves have the same frequency. One of the sound waves is traveling in air at 331 m/s and the other is traveling in water at 1450 m/s. What is the ratio of the wavelength of the sound in water to the wavelength of sound in air?
4.38
A hockey puck is given an initial speed of 10.0 m/s. It slides 50.0 m on the ice before it stops. What is the coefficient of kinetic friction between the puck and the ice?
0.10
A beaker is filled with 800 mL of water. A wooden cylinder will be placed into the beaker. If the wood’s density is 800 kg/m^3, what mass cylinder will raise the water level to the beaker’s maximum volume of 1000 mL?
200 g
A metal spherical shell with a charge +Q surrounds a point charge with a charge –Q. Rank the electric potentials at the lettered points (W, X, Y and Z). Assume 𝑉 → 0 as 𝑟 → ∞.
(Diagram 40)
VW < VX = VY = VZ
A submarine emits a sonar signal to detect the distance to, and velocity of, a second nearby submarine. Which pair of wave behaviors is most closely associated with these two measurements?
Reflection and Doppler Effect
A 2.0-kg mass suspended from a vertical spring stretches it a distance of 5.0 cm. The mass is then pulled down a distance of 10 cm and released. What is the frequency of oscillation?
2.25 Hz
A small sphere of mass m is attached to one end of a light string of length L with the other end of the string attached to a fixed point. The ball is moving at a constant speed v in a horizontal circle of radius r such that the string makes an angle theta with the vertical. Given that the tension in the string is T, what is the correct expression for the object's speed v?
v = sqrt(TLsin(theta)/m)
Wire A has a length of 2.0 m, a mass of 4.0 g, and it carries 10 A of current. The wire, which is parallel to the floor and can only move vertically, is placed above wire B that is carrying 15 A of current in the opposite direction. What separation distance between the two wires will allow the weight of wire A to be supported by magnetic force?
1.50 mm
A gas undergoes radioactive decay with time constant τ. A sample of 10000 particles is put into a container. After one time constant has passed, the experimenter adds another 10000 particles into the container. How much time passes from the addition of the particles until the container of gas reaches 10000 total particles again?
0.313 τ
An Atwood’s machine has two masses m1 and m2 connected by a light string passing over a pulley. If m1=5kg and m2=7kg, and the pulley has a radius of 0.1m, what is the tension in the string?
58.4 N
The Moon orbits the Earth on a nearly circular orbit with a period, T, of 27.3 days. The radius of orbit is 3.84 x 10^5 km. What is the acceleration of the Moon toward the Earth?
2.72 x 10^-3 m/s^2
In the circuit shown, the voltage source, switch, capacitor and connecting wires have no resistance. The switch is closed until the circuit achieves steady state, at which point the switch is opened. Which of the following statements about the potential differences after the switch is opened is true.
(Diagram 42)
a. The potential differences across the resistor and capacitor instantly become zero. b. The potential differences across the resistor and capacitor are equal at all times. c. The potential difference across the resistor increases, while the potential difference across the capacitor decreases. d. The potential difference across the resistor instantly becomes zero, while the potential difference across the capacitor remains unchanged. e. The potential difference across the resistor remains unchanged, while the potential difference across the capacitor instantly becomes zero
b. The potential differences across the resistor and capacitor are equal at all times.
An increase in the average speed of the molecules of a gas confined in a rigid cylinder will correspond to an…
a. increase in the temperature of the gas only. b. increase in the pressure of the gas only. c. increase in both the temperature and the pressure of the gas. d. increase in the temperature of the gas and a decrease in its pressure. e. increase in the pressure of the gas and a decrease in its temperature.
c. increase in both the temperature and the pressure of the gas.
When NASA began conducting test flights for the space shuttle, they used a “glider” that had a mass of 980 kg (including pilot). This glider was launched horizontally at 500 km/hr from a height of 3500 m. The glider eventually landed at a speed of 200 km/hr. What was the average force of air resistance exerted on the glider if it came in at a constant angle of 10º to the Earth?
2090 N
A solid, uniform disk and a solid, uniform sphere are placed on a ramp where they can roll without slipping. The disk is released a distance d from the bottom of the ramp and achieves a center-of-mass speed v upon reaching the bottom. From what distance (also measured from the bottom of the ramp) should the sphere be released to attain the same center-of-mass speed v at the bottom?
14/15 d
A drop of liquid is spherical and has a diameter of 2.0 mm. It is given a charge of 2.0 x 10^-15 C. This charged drop then combines with an identical uncharged drop and the two form one single drop. What is the electric potential at the surface of newly formed drop?
0.0143 V
A 432-Hz tuning fork is the lowest frequency tuning fork that can produce resonance when held over one end a certain plastic tube open at both ends. When one end of this tube is closed, which of the following tuning fork frequencies would produce resonance when held over the open end?
1080 Hz