Name: _______________________________________ ID: _________________

1.	Two masses m1 and m2 (with m2 > m1) are connected by a massless rope hung over a frictionless light pulley. If the masses are released then the acceleration of m2 in the downward direction is given by
	
A)	(m2 – m1) ´ g/(m1 – m2)	D)	m2 ´ g/(m1 + m2)	
B)	(m2 – m1) ´ g/(m1 + m2)	E)	g	
C)	(m1 + m2) ´ g/(m2 – m1)			

2.	A man riding in an elevator has an apparent weight (i.e., scale reading) greater than his actual weight.  Which one of the following statements could be true?	
A)	The elevator moves upward with constant speed.	
B)	The elevator moves downward with constant speed.	
C)	The elevator moves upward with decreasing speed.	
D)	The elevator moves downward with decreasing speed.	
E)	The elevator moves downward with increasing speed.	

3.	Two tug-of-war teams are pulling on the ends of a rope, each team with a force of 1000 N. If the rope does not move, the tension in the rope is	
	A)  2000 N    B)  500 N    C)  1000 N    D)  0 N    E)  2000 kg	

4.	A car going around a curve of radius R at a speed V experiences a centripetal acceleration ac.  What is its acceleration if it goes around a curve of radius 3R at a speed of 2V?	
	A)  (2/3)ac    B)  (4/3)ac    C)  (2/9)ac    D)  (9/2)ac    E)  (3/2)ac	

5.	A particle moving with uniform Motion Along a Curved Path has a period (i.e., time for one revolution) of 0.24 s and a speed of 4.2 m/s.  The radius of the path of the particle is	
	A)  16 cm    B)  2.6 cm    C)  1.0 m    D)  0.062 cm    E)  1.4 cm	

6.	A 5-kg object undergoes a displacement  During the displacement, a constant force  acts on the object. All values are given in SI units. The work done by the force  on this object is	
	A)  8 J    B)  –6 J    C)  2 J    D)  14 J    E)  –2 J	

7.	A block of mass, m, is pushed up against a spring, compressing it a distance x, and is then released.  The spring projects the block along a frictionless horizontal surface, giving the block a speed v.  The same spring projects a second block of mass 4m, giving it a speed 3v.  What distance was the spring compressed in the second case?	
A)	0.5
x	D)	4x	
B)	2x	E)	6x	
C)	3x			

8.	If vector  and a vector  the dot (i.e., inner) product  is	
	A)  –23    B)  7    C)  –7    D)  23    E)  17	

9.	A particle moves halfway around a circle of radius R.  It is acted on by a radial force of magnitude F.  The work done by the radial force is	
	A)  zero    B)  FR    C)  FpR    D)  2FR    E)  2pR	

10.	A 5-kg box is pushed 5 m up a plane that is inclined at 30º with the horizontal.  The coefficient of kinetic friction between the box and the plane is 0.20.  The change in potential energy of the box is approximately	
	A)  12.5 J    B)  34.2 J    C)  123 J    D)  345 J    E)  403 J	

11.	
 
A 5-kg mass with initial velocity 20 m/s slides along a frictionless horizontal surface then up a frictionless ramp (2 m long and at an angle 30 degrees to the horizontal) and onto a second horizontal surface (assume smooth transitions). The block slides over a rough surface 15 m in length (mk = 0.4) before moving again on a frictionless surface and then impacting upon an uncompressed spring. If the block compresses the spring a distance 2 m while coming to rest (momentarily), 	
	A)	What is the kinetic energy initially?

B)	What is the kinetic energy when it arrives onto the second horizontal surface?

C)	What is the work done by friction?

D)	What is the kinetic energy just before it contacts the spring?

E)	What is the spring constant k?	

Name_____________________________________ ID__________________________

12.	For this problem, assume no friction.  A mass m2 = 3.5 kg rests on a horizontal table and is attached by strings to masses m1 = 1.5 kg and m3 = 2.5 kg as shown.  The masses m1 and m3 hang freely.  The system is initially held at rest.  After it is released, 

	
	A) Draw the free body diagrams (i.e., show all the forces) for m1, m2, m3   

B) Write the equations of motion for  m1, m2, m3  

C) Find the acceleration for  m2

D) Find the tension in the left string

E) Find the tension in the right string	

Answer Key

1.	B:  m2g-m1g=(m2+m1)a →(m2-m1)g/ (m2+m1)=a	
2.	D:  must be upward acceleration so that upward scale force exceeds downward mg	
3.	C:  1000N	
4.	B:   ac=V2/R   a=(2V)2/(3R)=4V2/3R=4ac/3	
5.	A:   2πR=(4.2m/s)(.24s)   R=0.16m	
6.	C:   (4)(2)+(-2)(3)=2J	
7.	E:   ½mv2=½kx2 ,  ½(4m)(3v)2=½(36mv2)=½k36x2 =½kX2 ,  X=6x	
8.	A:   (-2)(4)+(3)(-5)=-23	
9.	A:   F is perpendicular to Δs 	
10.	C:   (5kg)(9.81m/s2)(5m)(sin30o)=123J	
11.	A)  ½5kg(20m/s)2=103J
B)   103J-(5kg)(9.81m/s2)(2m·sin30o)=951J
C)   (.4)(5kg)(9.81m/s2)(15m)=294.3J
D)   951J-294J=657J
E)   657J=½k(2m)2        k=328.5N/m
	
12.A)	 
B) (1) TL-m1g=m1a
     (2) TR-TL=m2a
     (3) m3g-TR= m3a
     (4) Fn-m2g=0
C)  add (1)+(2)+(3):   (m3-m1)g=(m1+m2+m3)a
                                         (1)g=(7.5)a               a=g/7.5=1.31m/s2
D)   (1)  TL=m1(a+g)=1.5kg(1.31+9.81)m/s2=16.7N
E)   (3)  TR=m3(g-a)=2.5kg(9.81-1.31)m/s2=21.3N