Section 1

The figure below shows velocity versus time graphs for objects A, B, and C - Rank the magnitude of each object's acceleration from greatest to least. Disregard the direction of the accelerations.

B&C are equal in terms of acceleration and are greater than A. The magnitude of an object's acceleration is found by taking the magnitude of the slope of the velocity versus time graph.

A driver ignores the stop sign and continues driving east at constant speed.

D

A driver, traveling west, slows and stops at the stop sign.

F

If an object is in motion and changes its position several times during a time interval, then the object's distance is _______ to the path length travelled.

Less than or equal

During which trial or trials is the object's velocity not constant?

The graph of the motion during Trial B has a changing slope and therefore is not constant. The other trials all have graphs with constant slope and thus correspond to motion with constant velocity.

If you could somehow increase the mass of an object, what would happen to the net force on the object?

The net force on an object doesn't depend on the object's mass.

As you accelerate upward in an elevator, which force exerted on you has the greatest magnitude?

The normal force from the elevator floor pushing up on you

Imagine a car sitting empty in the parking lot. Which of the following is the most complete list of the forces that belong on a free-body diagram (FBD) of the car?

The normal force on your car by the pavement it rests on and the force of gravity on your car by the earth

Newtons and kilograms are __________.

units for different quantities, and cannot be converted to each other

Which set of motion graphs is consistent?.

The velocity versus time graph is obtained by taking the slope of the position versus time graph. The acceleration versus time graph is obtained by taking the slope of the velocity versus time graph.

Under which circumstance is there a force exerted on the apple by your hand

When you are picking the apple up off the floor

What is the initial velocity of the particle, v0?

0.5 m/s

The graph below shows the velocity versus time for an object from t = 0 to t = 10 s. What is the total distance traveled by the object during this time interval?

30m. The total distance traveled is the area under the velocity versus time graph. To determine that area, break it up into suitable right triangles and rectangles. The area of a right triangle (AT ) is ½ bh, where b is the length of the base and h is the height of the triangle; the area of a rectangle (AR ) is wh, where w is the width of the rectangle and h is its height.

A driver ignores the stop sign and continues driving west at constant speed.

A

A person is standing still while leaning against the wall in a classroom. Which is the best answer regarding the number of forces exerted on her?

At least four

A driver, after stopping at the stop sign, travels east with a positive acceleration.

E

In order to state the force exerted on one object by another object, you must give

both the magnitude of the force and the direction of the force

What is the total distance Δx traveled by the particle?

Recall that the area of the region that extends over a time interval Δt under the v vs. t curve is always equal to the distance traveled in Δt. Thus, to calculate the total distance, you need to find the area of the entire region under the v vs. t curve. In the case at hand, the entire region under the v vs. t curve is not an elementary geometrical figure, but rather a combination of triangles and rectangles.

If you know all of the forces acting on an object and you know the mass of that object, what quantities can you figure out from that information?

The acceleration of the object

Which position (x) versus time (t) graph corresponds to the motion diagram shown below?

The position versus time graph for an accelerating object is a parabola. The parabola opens upward if the acceleration is positive, and it opens downward if the acceleration is negative.

During which trial or trials is the magnitude of the average velocity the largest?

While Trial B and Trial D do not have the same average velocity, the only difference is the direction! The magnitudes are the same. Neither one is "larger" than the other, and it is only because of how we chose our axes that Trial B has a positive average velocity while Trial D has a negative average velocity. In Trial C the object does not move, so it has an average velocity of zero. During Trial A the object has a positive average velocity but its magnitude is less than that in Trial B and Trial D.