Physics Tri I MCQ

An object with an unknown initial velocity has a constant acceleration with components a_x=8 m/s² and ay _{= 0}
Which of the following is a possible expression for the position of this object, in meters, for both the  and  directions as functions of time?

x = 4t² and y = 8t

The initial speed of Ball 1 is less than that of Ball 2. Which ball takes less time to return to the ground, and what evidence supports this claim?

Ball 2 takes less time. The maximum height it reaches is less than that of Ball 1.

A car is traveling down the highway at speed v when the driver slams on the brakes and skids to a stop in a distance d. Assuming the same frictional force, how far would the car slide if its speed was 2v?

4d

The speed v of an automobile moving on a straight road is given in meters per second as a function of time t in seconds by the following equation: . What is the acceleration of the automobile at t = 2 s?

24 m/s²

What do acceleration and velocity have in common?

Both are vectors

The position x of an object is given as a function of time t by the equation x = 8 + 4t – 6t³ , where x is in meters and t is in seconds. What is the maximum positive velocity attained by this object?

4 m/s

If air resistance is negligible, the height from which the package is released is

1/2g(x/v)²

Two projectiles are launched with the same initial speed from the same location, one at a 30° angle and the other at a 60° angle with the horizontal. They land at the same height at which they were launched. If air resistance is negligible, how do the projectiles' respective maximum heights, H30 and H60, and times in the air, T30 and T60 , compare with each other?

Maximum Height: H30 < H60 Time in Air: T30 < T60

The acceleration of the blocks is 0.6g. Assume that friction and the mass of the string are negligible. The ratio of masses M2/M1 is

1.5

At a particular instant, a stationary observer on the ground sees a package falling with speed at an angle to the vertical. To a pilot flying horizontally at constant speed relative to the ground, the package appears to be falling vertically with a speed  at that instant. What is the speed of the pilot relative to the ground?

√(v₁² - v₂²)

The blocks are pulled along a rough surface by a force of magnitude F exerted by string C. The coefficient of friction between each block and the surface is the same. Which string must be the strongest in order not to break?

C

The coefficient of friction between the block and the surface is \(\mu _{K}\). The force \(F\) that pulls the block is exerted at the angle \(\phi \) shown. Which of the following is an expression for the magnitude of the frictional force on the block if it is moving at constant speed?

μ_k (m g - F sin ϕ)

The coefficient of kinetic friction between the surface and the block is μ. Which of the following is a correct expression for the acceleration of the block?

a=g(sinθ−μcosθ

The acceleration due to gravity on the surface of the Moon is about 1/6 of that on the surface of Earth. An astronaut weighs 600 N on Earth. The astronaut's mass on the Moon is most nearly

60 kg

As the boy pulls himself upward, he applies a force F to the rope. Which of the following claims indicates a correct relationship between F and W and provides appropriate reasoning?

(F < W\), because as the boy exerts a force downward on the rope, the tension in the rope is pulling up on the boy and up on the bucket.

A car travels forward with constant velocity. It goes over a small stone, which gets stuck in the groove of a tire. The initial acceleration of the stone as it leaves the surface of the road, is

vertically upward

One student states that the collected data is not valid. Which of the following could be a valid explanation for the flawed data?

The incline is at an angle greater than 30°, increasing the acceleration from what was expected.

Which of the sets of figures is correct for the moment described above?

II and IV

The center of mass is located at position

(8/3, 1)

The magnitude of the force exerted on the block by the table is most nearly

29 N

A student of mass M is standing on a scale plate placed on the floor of an elevator. When the elevator is not moving, the reading N on the scale is N = mg. At some later time, the elevator is moving upward with speed v and slowing down with an acceleration of magnitude a. Based on these data, which of the following statements about N must be correct?

N = m(g-a)

A newly discovered planet is found to have twice the radius and five times the mass of Earth. If the acceleration of gravity at the surface of Earth is g, the acceleration of gravity at the surface of the new planet is

5g/4

The tension in the horizontal cord is . If the assembly is moved to the surface of a planet with the same average density and twice the radius of Earth, the new tension in the horizontal cord will be

𝟐𝑻𝑯

The position of a toy locomotive moving on a straight track along the \(x\)-axis is given by the equation \(x = t^3 - 6t^2 + 9t\), where \(x\) is in meters and \(t\) is in seconds. The net force on the locomotive is equal to zero when t is equal to

2 s

Two small spheres, each with a mass of 3.0 kg are placed 6.0 m apart. Which of the following is the order of magnitude of the gravitational attraction between them?

10^-11 N

In one trial, the initial speed of cart A is 2.5 m/s, and the initial speed of cart B is 1.5 m/s. The angle  relative to east that the carts travel after the collision is most nearly

22°

The surface and plane have negligible friction. The block is struck by a projectile of mass m traveling with a horizontal velocity . The projectile becomes embedded in the block, and they move together to the right with speed . Which of the following is a correct expression for ?

m/(m+M)vi

If the blocks are then released and the block of mass 2M leaves the spring with a velocity v, the velocity of the center of mass of the blocks is

zero

The change in momentum of the object from time 0 to t is

1/2𝐹𝑡

0.67 kg

A balloon of mass M is floating motionless in the air. A person of mass less than M is on a rope ladder hanging from the balloon. The person begins to climb the ladder at a uniform speed v relative to the ground. How does the balloon move relative to the ground?

Down with a speed less than v

The second disc is moving horizontally to the right with speed v/2 at the moment of impact. The two discs stick together upon impact. The speed of the composite body immediately after the collision is

2v/3

Does the graph provide sufficient information to determine the change in momentum of the cart during the time interval shown, and what evidence supports the claim?

Yes, because the change in momentum is equal to the area under the curve of the force-versus-time graph.

A particle of mass m starts from rest at position x = 0 and time t = 0. It moves along the positive x-axis under the influence of a single force Fx= bt, where b is a constant. The velocity v of the particle is given by

𝑏𝑡²⁠/2m

A ball of mass m is dropped from rest at a height h and collides elastically with the floor, rebounding to its original height. What is the magnitude of the net impulse on the ball during the collision with the floor?

𝑚√8𝑔ℎ

A student drops a bag of mass m onto a cart of mass M that is sliding with speed v_o along a horizontal track with negligible friction. Immediately after the bag lands in the cart, the cart-bag system moves with speed v_f. Which of the following statements correctly relates the two speeds and gives a correct reason for this relationship?

v_f < v_o , because some of the cart-bag system's mechanical energy is dissipated.