Question 1

A block of mass m is pulled in the direction shown in the figure across a rough surface with a constant acceleration   .The magnitude of the frictional force is

Accepted Answer

A) µkmg 
B) T cos $\theta$ - ma 
C) µk(T - mg) 
D) µkT sin $\theta$ 
E) µk(mg + sin $\theta$) 
A) µkmg 
B) T cos $\theta$ - ma 
C) µk(T - mg) 
D) µkT sin $\theta$ 
E) µk(mg + sin $\theta$)

Question 2

Four smiley faces are situated along the x axis as follows: m1 = 5 kg at -5.0 m,m2 = 3 kg at -2.0 m,m3 = 3 kg at 1.0 m,and m4 = 2 kg at 3.0 m.Where is the center of mass situated?

Accepted Answer

A) 3.1 m 
B) 0.0 m 
C) -1.7 m 
D) -0.80 m 
E) -3.1 m 
A) 3.1 m 
B) 0.0 m 
C) -1.7 m 
D) -0.80 m 
E) -3.1 m

Question 3

A 50-kg block rests on a horizontal surface.The coefficient of static friction $\mu$a = 0.50.The coefficient of kinetic friction $\mu$k = 0.35.A force   of 250 N is applied as shown.

Accepted Answer

A) The block remains at rest. 
B) The block moves and continues to move at constant velocity. 
C) The block accelerates to the right. 
D) The block does not move until   is increased to greater than 490 N. 
E) No conclusions can be drawn concerning the movement of the block from the information given. 
A) The block remains at rest. 
B) The block moves and continues to move at constant velocity. 
C) The block accelerates to the right. 
D) The block does not move until   is increased to greater than 490 N. 
E) No conclusions can be drawn concerning the movement of the block from the information given.

Question 4

Use the figure below for the problem. A mass, mS1U1B11S1U1B0, attached to a spring is placed on a cart with mass mS1U1B12S1U1B0, which moves freely and without friction on a table. mS1U1B11S1U1B0 slides without friction on the cart and is ¼ the mass of mS1U1B12S1U1B0. 
-When m1 moves with a displacement of 1 cm in the +x direction,what is the displacement of m2?

Accepted Answer

A) m2 does not move 
B) m2 moves   cm in the +x direction 
C) m2 moves 1 cm in the +x direction 
D) m2 moves   cm in the -x direction 
E) m2 moves 1 cm in the -x direction 
A) m2 does not move 
B) m2 moves   cm in the +x direction 
C) m2 moves 1 cm in the +x direction 
D) m2 moves   cm in the -x direction 
E) m2 moves 1 cm in the -x direction

Question 5

A car experiences both a centripetal and a tangential acceleration.For which of the following would this be true?

Accepted Answer

A) It is going around a curve at a constant speed. 
B) It is going around a curve and slowing down. 
C) It is going along a straight road at a constant speed. 
D) It is going along a straight road and increasing its speed. 
E) It is going along a straight road and decreasing its speed. 
A) It is going around a curve at a constant speed. 
B) It is going around a curve and slowing down. 
C) It is going along a straight road at a constant speed. 
D) It is going along a straight road and increasing its speed. 
E) It is going along a straight road and decreasing its speed.

Question 6

A block of mass m is pulled in the direction shown in the figure across a rough surface at a constant velocity.The magnitude of the frictional force is

Accepted Answer

A) µkmg 
B) µkT cos $\theta$ 
C) µk(T - mg) 
D) µkT sin $\theta$ 
E) µk(mg - T sin $\theta$) 
A) µkmg 
B) µkT cos $\theta$ 
C) µk(T - mg) 
D) µkT sin $\theta$ 
E) µk(mg - T sin $\theta$)

Question 7

When a particle moves in a circle with constant speed,its acceleration is

Accepted Answer

A) constantly increasing. 
B) constant in direction. 
C) zero. 
D) constant in magnitude. 
E) constant in magnitude and direction. 
A) constantly increasing. 
B) constant in direction. 
C) zero. 
D) constant in magnitude. 
E) constant in magnitude and direction.

Question 8

A boy is standing at the stern (back)of a boat that is 8.0 m long.There is no friction between the boat and the water.The boy has a mass of 63 kg and the boat has a mass of 780 kg.The bow (front)of the boat is touching a dock and the fore-and-aft axis of the boat is perpendicular to the dock.The boy walks from the stern of the boat to the bow.When he reaches the bow,his distance from the dock is

Accepted Answer

A) 7.6 m 
B) 0.65 m 
C) 0.51 m 
D) 0.56 m 
E) 1.3 m 
A) 7.6 m 
B) 0.65 m 
C) 0.51 m 
D) 0.56 m 
E) 1.3 m

Question 9

The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path.Assume that air resistance is negligible.The free-body diagram that best represents the net force acting on the ball is

Accepted Answer

A) 1 
B) 2 
C) 3 
D) 4 
E) 5 
A) 1 
B) 2 
C) 3 
D) 4 
E) 5

Question 10

A uniform horizontal bar is in a region of space where the acceleration due to gravity g varies,increasing from left to right.Where is the location of the center of mass relative to the center of gravity?

Accepted Answer

A) They are at the same location. 
B) The center of mass is to the left of the center of gravity. 
C) The center of gravity is to the left of the center of mass. 
D) It depends on the shape of the bar. 
E) It depends on how much g changes. 
A) They are at the same location. 
B) The center of mass is to the left of the center of gravity. 
C) The center of gravity is to the left of the center of mass. 
D) It depends on the shape of the bar. 
E) It depends on how much g changes.

Question 11

A barbell is 1.5 m long.Three weights,each of mass 20 kg,are hung on the left and two weights of the same mass,on the right.The width of each weight is 4 cm and each group of weights is placed 4 cm from the ends.Where is the center of mass of the barbell as measured from the mid-point,M,of the bar? The bar is of uniform mass and has mass 5 kg,and the retaining collars are of negligible mass.Take to the right as positive.

Accepted Answer

A) -5.90 cm 
B) -5.62 cm 
C) +5.62 cm 
D) +5.90 cm 
E) None of the above 
A) -5.90 cm 
B) -5.62 cm 
C) +5.62 cm 
D) +5.90 cm 
E) None of the above

Question 12

A mass m2 = 1.5 kg rests on a horizontal table.The coefficients of friction between m2 and the table are µs = 0.3 and µk = 0.25.The mass m2 is attached by strings to masses m1 = 2.5 kg and m3 = 4.5 kg as shown.Masses m1 and m3 hang freely.The system is initially held at rest.After it is released,the acceleration of m2 is approximately

Accepted Answer

A) 1.9 m/s2  
B) 2.4 m/s2  
C) 3.0 m/s2  
D) zero 
E) 13 m/s2  
A) 1.9 m/s2  
B) 2.4 m/s2  
C) 3.0 m/s2  
D) zero 
E) 13 m/s2

Question 13

The SI units for the coefficient of friction are

Accepted Answer

A) newtons per meter. 
B) meters. 
C) newtons. 
D) newtons times meters. 
E) None of these is correct; the coefficient of friction has no units. 
A) newtons per meter. 
B) meters. 
C) newtons. 
D) newtons times meters. 
E) None of these is correct; the coefficient of friction has no units.

Question 14

An object with a mass of m = 12.0 g is falling through a resistive fluid in which g is constant.The retarding frictional force due to the fluid is F = bv,where F is the force in newtons,b is a constant,and v is the speed in meters per second.If F = 3.2 $\times$ 10-2 N when v = 16.0 m/s,the terminal speed of the object falling through the fluid is

Accepted Answer

A) 0.12 m/s 
B) 59 m/s 
C) 0.19 km/s 
D) 16.0 m/s 
E) None of these is correct. 
A) 0.12 m/s 
B) 59 m/s 
C) 0.19 km/s 
D) 16.0 m/s 
E) None of these is correct.

Question 15

The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path.The speed of the ball is constant.If the string should break at the instant shown,the path that the ball would follow is

Accepted Answer

A) 1 
B) 2 
C) 3 
D) 4 
E) impossible to tell from the given information. 
A) 1 
B) 2 
C) 3 
D) 4 
E) impossible to tell from the given information.

Question 16

A 50-kg box is placed in the bed of a truck.The coefficient of friction between the box and the truck bed is 0.54.If the truck is traveling at 87 km/h (~54 mph)then calculate the minimum distance the truck can stop in without the box sliding into the cab.

Accepted Answer

A) 99 m 
B) 1.4 $\times$ 103 m 
C) 55 m 
D) 1.2 $\times$ 102 m 
E) 2.8 $\times$ 102 m 
A) 99 m 
B) 1.4 $\times$ 103 m 
C) 55 m 
D) 1.2 $\times$ 102 m 
E) 2.8 $\times$ 102 m

Question 17

The picture on the right shows an exploding firework high up in the air,just after the firework has come to a rest.Which point best describe the center of mass of the explosion?   Picture by H.K.Ng

Accepted Answer

A) a 
B) b 
C) c 
D) d 
E) e 
A) a 
B) b 
C) c 
D) d 
E) e

Question 18

In drag racing,the driver deploys a parachute at the end of the   mile run.The parachute works well because

Accepted Answer

A) the dragster does not have any brakes to save weight. 
B) the drag force due to the parachute is large at high speeds. 
C) there is no rolling friction at high speeds. 
D) the driver has no time to apply the brakes. 
E) the deployment of the parachute is part of the show. 
A) the dragster does not have any brakes to save weight. 
B) the drag force due to the parachute is large at high speeds. 
C) there is no rolling friction at high speeds. 
D) the driver has no time to apply the brakes. 
E) the deployment of the parachute is part of the show.

Question 19

A box (M = 20 kg)is sitting on a horizontal surface.It is connected to a massless hook by a light string passing over a massless pulley wheel.The coefficients of friction between the box and the surface are 0.80 (static)and 0.30 (kinetic).If 15 kg (in total)are placed on the hook,calculate the acceleration of the box.

Accepted Answer

A) 10 m/s 
B) 4.4 m/s 
C) 2.5 m/s 
D) 12 m/s 
E) 0 
A) 10 m/s 
B) 4.4 m/s 
C) 2.5 m/s 
D) 12 m/s 
E) 0

Question 20

A mass m is placed on a rough incline at an angle $\theta$ to the horizon.A force F is applied up the incline so that the mass slides up the incline.Using the compass rose,the direction of the frictional force is along

Accepted Answer

A) (a) 
B) (b) 
C) (c) 
D) (d) 
E) (e) 
A) (a) 
B) (b) 
C) (c) 
D) (d) 
E) (e)

Exam 5: Applications of Newtons Laws

A block of mass m is pulled in the direction shown in the figure across a rough surface with a constant acceleration .The magnitude of the frictional force is

Four smiley faces are situated along the x axis as follows: m1 = 5 kg at -5.0 m,m2 = 3 kg at -2.0 m,m3 = 3 kg at 1.0 m,and m4 = 2 kg at 3.0 m.Where is the center of mass situated?

A 50-kg block rests on a horizontal surface.The coefficient of static friction μ\muμ a = 0.50.The coefficient of kinetic friction μ\muμ k = 0.35.A force of 250 N is applied as shown.

A car experiences both a centripetal and a tangential acceleration.For which of the following would this be true?

A block of mass m is pulled in the direction shown in the figure across a rough surface at a constant velocity.The magnitude of the frictional force is

When a particle moves in a circle with constant speed,its acceleration is

The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path.Assume that air resistance is negligible.The free-body diagram that best represents the net force acting on the ball is

A uniform horizontal bar is in a region of space where the acceleration due to gravity g varies,increasing from left to right.Where is the location of the center of mass relative to the center of gravity?

The SI units for the coefficient of friction are

The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path.The speed of the ball is constant.If the string should break at the instant shown,the path that the ball would follow is

A 50-kg box is placed in the bed of a truck.The coefficient of friction between the box and the truck bed is 0.54.If the truck is traveling at 87 km/h (~54 mph)then calculate the minimum distance the truck can stop in without the box sliding into the cab.

The picture on the right shows an exploding firework high up in the air,just after the firework has come to a rest.Which point best describe the center of mass of the explosion? Picture by H.K.Ng

In drag racing,the driver deploys a parachute at the end of the mile run.The parachute works well because

A mass m is placed on a rough incline at an angle θ\thetaθ to the horizon.A force F is applied up the incline so that the mass slides up the incline.Using the compass rose,the direction of the frictional force is along

Systems of Measurement

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Newtons Laws

Work and Energy

Conservation of Energy

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Filters

Four smiley faces are situated along the x axis as follows: m₁ = 5 kg at -5.0 m,m₂ = 3 kg at -2.0 m,m₃ = 3 kg at 1.0 m,and m₄ = 2 kg at 3.0 m.Where is the center of mass situated?