PHY_10_V2_DM_Revision term 1 (1)

Kinematics:

1.      Little Joey plays with his remote control car, and generates the motion graph below. The car starts by moving eastwards.

a.       Identify section(s) where the car moves with constant velocity.

b.      Identify section(s) where the car moves west.

c.       Identify section(s) where the car speeds up.

d.      When is the car at rest?

e.       What is the average velocity of the car between 0 and 15 seconds?

f.        What is the average speed of the car in the same time interval?

g.      What is the total displacement of the car from 0 to 22 seconds?

h.      Draw a velocity vs. time graph describing the motion of the car.

Dynamics:

1.      A space station astronaut is working outside the station as it orbits the earth. If he drops a hammer, will it fall to earth? Explain why or why not.

2.      The free-fall acceleration at the surface of planet 1 is 20 m/s2. The radius and the mass of planet 2 are twice those of planet 1. What is g on planet 2?

3.      Why is the gravitational potential energy of two masses negative? Note that saying “because that’s what the equation gives” is not an explanation.

Momentum:

(a)                   Two skaters, each of mass 40 kg, approach each other along parallel paths that are separated by a distance of 2 m.  Both skaters have a speed of 10 m/s.

(b)                               The first skater carries a 2-m pole that may be considered massless.  As he passes the pole, the second skater catches hold of the end.  The two skaters then go around in a circle about the center of the pole.

1.What is the angular speed of the skaters after they have linked together?

(c)                                4 rad/s                               (c)  10 rad/s           (e)              40 rad/s

(d)                               5 rad/s                               (d) 20 rad/s

2.      What is their combined angular momentum about the center of the pole?

(a)                                2 kg × m²/s                         (c)  80 kg × m²/s                       (e)  800 kg × m²/s  

(b)                               40 kg × m²/s                       (d) 400 kg × m²/s

3.      A 2.0-kg hoop rolls without slipping on a horizontal surface so that its center proceeds to the right with a constant linear speed of 6.0 m/s.

Which one of the following statements is true concerning the angular momentum of this hoop?

(a)                                It points into the paper.           (d)             It points to the right.

(b)                               It points out of the paper.           (e)           It varies from point to point on the hoop.

(c)                                It points to the left. 

Mechanics of liquids and gases:

 Fire hoses used in major structure fires have inside diameters of 6.40 cm. Suppose such a hose carries a flow of 40.0 L/s starting at a gauge pressure of 1.62×106N/m2. The hose goes 10.0 m up a ladder to a nozzle having an inside diameter of 3.00 cm. Assuming negligible resistance, what is the pressure in the nozzle?