2021
A brick is moving at a speed of 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the pebble's mass?
25:9
Consider a situation where the acceleration of an object is always directed perpendicular to its velocity. This means that
(A) the object is increasing speed. (B) the object is decreasing speed. (C) the object is not moving. (D) the object is turning. (E) this situation would not be physically possible.
(D) the object is turning.
Which of the following is NOT a vector quantity?
(A) Acceleration (B) Average velocity (C) Linear momentum (D) Potential energy (E) Force
(D) Potential energy
A small object is released from rest and falls freely for 4.00 𝑠 until reaching the ground. What was the height above the ground from which the object was released?
80.0 m
Any nucleus that emits an alpha particle or beta particle
A) always becomes a nucleus of a different element B) may become a nucleus of a different element C) becomes a different isotope of the same element D) increases its mass number E) increases its mass
A) always becomes a nucleus of a different element
A simple and correct way to comprehend satellites orbiting Earth is to view them as
A) balanced between gravitational and centripetal forces. B) beyond the main pull of Earth’s gravity. C) in mechanical equilibrium with a net force of zero. D) having sufficient tangential velocities to fall around rather than into Earth. E) All of the above.
D) having sufficient tangential velocities to fall around rather than into Earth.
A coin of mass m is dropped straight down from the top of a very tall building. As the coin approaches terminal speed, the net force on the coin is
(A) upward. (B) 0. (C) downward, with magnitude less than mg. (D) downward, with magnitude equal to mg. (E) downward, with magnitude greater than mg.
(C) downward, with magnitude less than mg.
An object of mass m is initially at rest. After this object is accelerated to a speed of 2.40 x 108 m/s, it collides with and sticks to a second object of mass m that is at rest. Immediately after the collision, what is the common speed of the two masses? (3 sig figs)
1.50 x 108 m/s
A 4.00 𝑘𝑔 object moves to the right with speed 5.00 𝑚/𝑠. A 5.00 𝑘𝑔 object moves to the left with speed 3.00 𝑚/𝑠. After colliding, the 4.00 𝑘𝑔 object moves to the left with speed 1.00 𝑚/𝑠. What is the speed of the 5.00 𝑘𝑔 object after the collision? (3 sig figs)
1.80 m/s
Related to the historical development of understanding gravity, which is the proper chronological order for the work of these three scientists, from earliest to latest? (A) Cavendish, Galileo, Newton (B) Galileo, Cavendish, Newton (C) Galileo, Newton, Cavendish (D) Newton, Galileo, Cavendish (E) Newton, Cavendish, Galileo
(C) Galileo, Newton, Cavendish
A rock that has a mass of 12 kg is sliding on a rough, horizontal surface. It has 24 J of kinetic energy and the friction force on it is a constant 0.50 N. What distance will it slide before coming to rest?
48 m
A horizontal disk has a spring and a mass attached to a rod passing through its center. The spring has a spring constant of k and the attached mass is m. When the disk is not rotating, the equilibrium length of the spring is d. The disk is now angularly accelerated until it reaches a constant angular velocity of w. At this angular velocity the length of the spring is now 2d. What is the angular velocity of the disk?
(B) √ 𝑘 /2m
An Olympic bobsled needs to negotiate a 100 m radius turn at 35 m/s without skidding. What minimum banking angle of the turn is needed for this to happen? (Ignore friction.)
51°
A 4.00 𝑘𝑔 mass is in uniform circular motion as shown in the figure. The string to which the mass is attached has a length of 𝐿 = 3.00 𝑚 and forms an angle of 𝜃 = 50.0° with the vertical. What is the speed of the mass? (3 sig figs)
5.23 m/s
In physics experiments located deep underground, the two types of cosmic rays that most commonly reach the experimental apparatus are:
(A) alpha particles and neutrons (B) protons and electrons (C) iron nuclei and carbon nuclei (D) muons and neutrinos (E) positrons and electrons
(D) muons and neutrinos
Two satellites are in circular orbits around a star with equal radius r, speed v, and period T. The satellites are initially diametrically opposite each other. In order to meet the second satellite in time T /2, the first satellite should decrease its speed to approximately x * v. What is the value of x?
0.64
A curve on a racetrack has a radius of 80 m and is banked at 45°. Suppose that the road surface on the curve somehow became frictionless (perhaps caused by an ice storm or an oil spill) and a car needs to navigate this curve. What is the safe speed with which to take the curve without either sliding up or down the bank of the curve? (round to nearest integer)
28 m/s
A packing crate with mass m = 115 kg is slid up a 5.00 m long ramp which makes an angle of 20° with respect to the horizontal by an applied force of F = 1.00 × 103 N directed parallel to the ramp’s incline. A frictional force of magnitude f = 4.00 × 102 N resists the motion. If the crate starts from rest, what is its speed at the top of the ramp? (3 sig figs)
4.24 m/s
A projectile is launched with speed v0 off the edge of a cliff of height h, at an angle θ from the horizontal. Air friction is negligible. To maximize the horizontal range of the projectile, θ should satisfy
(A) 45° < θ < 90° (B) θ = 45° (C) 0° < θ < 45° (D) θ = 0° (E) θ < 45° or θ > 45° , depending on the values of h and v0.
(C) 0° < θ < 45°
Which of the following scientists was awarded a Nobel Prize in Physics in 1956 and again in 1972?
A) John Bardeen B) Enrico Fermi C) Murray Gell-Mann D) Hans Bethe E) Wolfgang Pauli
A) John Bardeen
Spaceman Fred’s trusty pellet sprayer is held at rest a distance h away from the center of Planet Orb, which has radius R much smaller than h. The pellet sprayer ejects pellets radially outward, uniformly in the plane of the page. These pellets are all launched with the same speed v, so that a pellet launched directly away from Orb by the pellet sprayer can just barely escape it. What fraction of the pellets eventually lands on Orb? (Hint: you may use the small angle approximation, sin θ ≈ θ for θ much smaller than 1, where θ is in radians.)
(2nd Hint: there will be pi's and R's and h's in your answer, and a possible square root)
(1/pi) * sqrt(R/h)
A wheel of radius R is rolling without slipping with angular velocity omega. For point A on the wheel at an angle theta with respect to the vertical, what is the magnitude of its velocity with respect to the ground?
2*omega*R*sin(theta/2)
The hard disk in a computer will spin up to speed within 10 rotations, but when turned off will spin through 50 rotations before coming to a stop. Assuming the hard disk has constant angular acceleration α1 and angular deceleration α2, the ratio α1/α2 is what?
5
A ball of mass m moving at speed v collides with a massless spring of spring constant k mounted on a stationary box of mass M in free space. No mechanical energy is lost in the collision. If the system does not rotate, what is the maximum compression x of the spring? (yes, it's gross, I'm sorry)
(not really)
x = v √ [(mM)/(m+M)k]
Why does the sky appear to be more blue when looking directly overhead than it does when looking toward the horizon?
(A) The atmosphere is denser at higher altitude than it is at the Earth's surface. (B) The temperature of the upper atmosphere is higher than it is at the Earth's surface. (C) There are fewer clouds directly overhead than near the horizon. (D) The sunlight travels over a longer path at the horizon, resulting in more scattering. (E) The sunlight entering the atmosphere from directly above undergoes greater refraction and dispersion.
(D) The sunlight travels over a longer path at the horizon, resulting in more scattering.