Question 1

1) The position $$x (in $$meters) of an object is given by the equation $$x = A + Bt + Ct^2$, where t$ represents time in seconds. What are the SI units of A$, B$, and C$?

Accepted Answer

$$A$$: m, $$B$$: m/s, $$C$$: $$m/s^2$$

Question 2

2) If all the components of a vector are equal to 1, then that vector is a unit vector.

Accepted Answer

False

Question 3

3) If you set the cruise control of your car to a certain speed and take a turn, the speed of the car will remain the same. Is the car accelerating?

Accepted Answer

Yes

Question 4

4) Two objects are thrown from the top of a tall building and experience no appreciable air resistance. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street?

Accepted Answer

They are traveling at the same speed.

Question 5

5) A ball is thrown directly upward and experiences no air resistance. Which statement about its motion is correct?

Accepted Answer

The acceleration is downward during the entire time the ball is in the air.

Question 6

6) The position of an object is given by $$x = at^2$ + ct$$, where $$a = 1\ \mathrm{m/s^2$}$$, $$c = 2\ \mathrm{m/s}$$, and $$t is in $$seconds. What is the instantaneous acceleration of the object when $$t = 2.0\ \mathrm{s}$$?

Accepted Answer

$$2\ \mathrm{m/s^2$}$$

Question 7

7) Object A has a position as a function of time given by $$r(t) = (3.00\ \mathrm{m/s^2$})t\hat{i} - (1.00\ \mathrm{m/s^2$})t^2$\hat{j}. $$All quantities are SI units. What is the acceleration of the object at time $$t = 3.00\ \mathrm{s}$$?

Accepted Answer

$$a = 0\hat{i} - 2.00\ \mathrm{m/s^2$}\hat{j}$$

Question 8

8) An object moves in a circle of radius $$R at $$constant speed with a period of $$4\ \mathrm{s}. If $$you want to change only the period in order to cut the object's acceleration in half, the new period should be:

Accepted Answer

$$4\sqrt{2}\ \mathrm{s}$$

Question 9

9) In physics, the dimension of a physical quantity is often expressed in terms of $$L$$, $$M$$, and $$T. In $$the equation $$x = x_0$ + Ct^2$, what is the dimension of C$?

Accepted Answer

$$L T$$^{-2}$$

Question 10

10) In the formula for the average velocity $$\Delta X / \Delta t$$, what does $$\Delta X$$ represent?

Accepted Answer

The change in position

Question 11

11) A hockey puck slides off the edge of a table with an initial velocity of $$28.0\ \mathrm{m/s}$$ and experiences no air resistance. The height of the tabletop above the ground is $$2.00\ \mathrm{m}. $$What is the angle below the horizontal of the velocity of the puck just before it hits the ground?

Accepted Answer

$$4.0^\circ$$

Question 12

12) An object is thrown horizontally from a height $$h$$ with initial speed $$v_0. $$Neglecting air resistance, what is the time it takes to hit the ground?

Accepted Answer

$$t = \sqrt{\frac{2h}{g}}$$

Question 13

13) A car moves in a circle of radius $$R at $$constant speed $$v. $$What is the direction of its acceleration?

Accepted Answer

Radially inward toward the center

Question 14

14) The $$x-$$component of a velocity vector is $$18.05\ \mathrm{m/s}$$ and the $$y-$$component is $$10.75\ \mathrm{m/s}. $$What is the magnitude of the velocity vector?

Accepted Answer

$$20.99\ \mathrm{m/s}$$

Question 15

15) If the $$x-$$component of the average velocity vector over a time interval is $$15\ \mathrm{m/s}$$ and the $$y-$$component is $$-5\ \mathrm{m/s}$$, what is the direction of the average velocity vector relative to the $$x-$$axis?

Accepted Answer

$$\arctan\left(\frac{-5}{15}\right)$$ below the $$x-$$axis

Kinematics and Dimensional Analysis: Physics Study Notes

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