Misconceptual Questions

To convert from ft^2 to yd^2

multiply by 1/3

You drive 4 km at 30 km/h and then another 4 km at 50 km/h. What is your average speed for the whole 8-km trip? a. More than 40 km/h. b. Equal to 40 km/h. c. Less than 40 km/h. d. Not enough information.

c. Less than 40 km/h

In which of the following cases does a car have a negative velocity and a positive acceleration? A car that is traveling in the a) -x direction at constant 20 m/s b) -x direction increasing speed c) +x direction increasing speed d) -x direction decreasing in speed e) +x direction decreasing in speed

-x direction decreasing in speed

You are in the middle of a large field. You walk in a straight line for 100 m, then turn left and walk 100 m more in a straight line before stopping. When you stop, you are 100 m from your starting point. By how many degrees did you turn? 90, 120, 30, 180

120 60 makes an equilateral triangle

You are adding vectors of length 20 and 40 units. Which of the following choices is a possible resultant magnitude? 0, 18, 37, 64, 100

37

Four students use different instruments to measure the length of the same pen. Which measurement implies the greatest precisions? a. 160.0 mm b. 16.0cm c. 0.160 m d. 0.00016km

a. 160.0 mm

You drop a rock off a bridge. When the rock has fallen 4 m, you drop a second rock. As the two rocks continue to fall, what happens to their velocities? a. Both increase at the same rate. b. The velocity of the first rock increases faster than the velocity of the second. c. The velocity of the second rock increases faster than the velocity of the first. d. Both velocities stay constant.

a. Both increase at the same rate

The magnitude of a component of a vector must be a. less than or equal to the magnitude of the vector b. equal to the magnitude of the vector c. greater than or equal to the magnitude of the vector d. less than, equal to, or greater than the magnitude of the vector

a. less than or equal to the magnitude of the vector

L^2 represents the dimensions for which of the following? a. cm^2 b. square feet c. m^2 d. all of the above

all of the above

A ball is thrown downward at a speed of 20 m/s. Choosing the +y axis pointing up and neglecting air resistance, which equation(s) could be used to solve for other variables? The acceleration due to gravity is g = 9.8 m/s^2 downward. a. v = (20 m/s) - gt b. y = y_0 + (-20 m/s)t - (1/2)gt^2 c. v^2 = (20 m/s^2) - 2g(y - y_0) d. (20 m/s) = (v + v_0)/2e. all of the above

b. y = y_0 + (-20 m/s)t - (1/2)gt^2 c. v^2 = (20 m/s^2) - 2g(y - y_0)

Order-of-magnitude estimation will not always

be accurate to at least two sig figs

A ball is dropped from the top of a tall building. At the same instant, a second ball is thrown upward from the ground level. When the two balls pass one another, one on the way up, the other on the way down, compare the magnitudes of their acceleration: a. The acceleration of the dropped ball is greater. b. The acceleration for the ball thrown upward is greater. c. The acceleration of both balls is the same. d. The acceleration changes during the motion, so you cannot predict the exact value when the two balls pass each other.e. The accelerations are in opposite directions.

c. The acceleration of both balls is the same

A ball is thrown straight up. What are the velocity and acceleration of the ball at the highest point in its path? a. v = 0, a = 0. b. v = 0, a = 9.8 m/s^2 up. c. v = 0, a = 9.8 m/s^2 down. d. v = 9.8 m/s up, a = 0.

c. v = 0, a = 9.8 m/s^2 down.

At time t = 0 an object is traveling to the right along the +x axis at a speed of 10.0 m/s with acceleration -2.0 m/s^2. Which statement is true? a. The object will slow down, eventually coming to a complete stop. b. The object cannot have a negative acceleration and be moving to the right. c. The object will continue to move to the right, slowing down but never coming to a complete stop. d. The object will slow down, momentarily stopping, then pick up speed moving to the left.

d. The object will slow down, momentarily stopping, then pick up speed moving to the left.

A student's weight displayed on a digital scale is 177.2 lb. This would suggest her weight is a. within 1% of 177.2 lb. b. exactly 117.2 lb. c. somewhere between 117.18 and 117.22 lb. d. somewhere between 117.0 and 1117.4 lb.

d. somewhere between 117.0 and 1117.4 lb.

Accuracy represents

how close a measurement is to the true value