Physics I "old" material MC

consider a person standing in an elevator that is moving downward and slowing down. the net force on the person is…

up

which statement about the velocity for 0 < t < 4s is correct for the graph of velocity versus time shown at the right?

v changes sign after t = 2s

can two vectors having different magnitudes be combined to give a vector sum of zero?

no

in the figure at the right, the magnitude of the component of F sub 1 perpendicular to the incline is given by

F sub 1 cos theta

You are sitting in a car that begins to accelerate in the forward direction. Which of the following statements is correct?

The seat pushes forward on you to cause your acceleration

If you drop an object in the absence of air resistance, it accelerates downward at 9.8m/s². If instead you throw it downward, its downward acceleration is…

equal to 9.8m/s²

A lamp is suspended by a cable from the ceiling in an elevator. If the elevator is descending and speeding up, what is the relationship between the tension in the cable (T) and the weight (mg) of the lamp?

T < mg

The figure shows a flat-bed truck that starts from rest and accelerates to the right as shown. A crate on the truck is tied with cables that exert forces T1 and T2 on the crate as shown. If we assume that there is no friction between the crate and the truck, then

T1 < T2

A battleship simultaneously fires two shells at enemy ships. If the shells follow the parabolic trajectories shown, which ship gets hit first?

Time in the air is determined by the maximum height

An object is traveling in the negative x-direction and slowing down. The acceleration is..

positive

The figure shows a flat-bed truck with a crate of mass m that is not tied down. The truck and crate are moving to the right and speeding up (slowly so the crate does not slide). The frictional force acting on the crate is given by

F sub friction = m|a| to the right

You are standing in an elevator that is moving upwards and slowing down. The work down by the normal force is

positive

As the skydiver shown at the right falls faster and faster through the air, the net force

decreases

A ball of mass m is loaded into a toy gun, the spring is compressed a distance x and the ball is fired vertically into the air. If a ball of mass 2m is loaded into the gun and the spring is compressed the same amount, the second ball will go

1/2

Two identical objected are tied together with a string and swung around in a horizontal circle as shown. The tension T1 in the string is related to the tension T2 according to

T1 > T2

Identical forces are applied to two objects that are initially at rest on a frictionless table. Object B has a mass that is twice that of object A. If the force is applied to each block for an equal time, which block has the greater momentum?

same

In the example above, which block has the larger kinetic energy?

A

The Ferris wheel shown at the right is rotating counterclockwise at a constant speed. Draw a vector on the figure showing the direction of the net force on a rider at point P.

Left

A hard rubber ball is thrown with a velocity v in the positive x-direction toward a wall. It bounces directly back with a speed equal to -v. The work done on the ball during collision is

equal to 0

Two identical springs are arranged in the configurations shown at the right. The potential energy stored in the spring in configuration (a) is

4 times