Chapter 8

A 2kg mass is projected vertically upward from ground level with initial speed of 30m/s... a. -.21 kJ b. -.47 c. -.4 d. -.34 e. -.69

A. -.21 kJ

A 1.5kg block sliding on a rough hor. surface is attached to one end of a hor. spring (k=22N/m)... a. .34 b. .24 c. .13 d. .44 e. .17

A. .34

A 1.2 kg mass is projected from ground level with v=30m/s at some unknown angle above horiz... KE? a. .35 kH b. .73 c. .4 d. .68 e. .19

A. .35 kH

A 12 kg block on a horizontal frictionless surface is attached to a spring (Fconstant=.8 kN/m). The block initially at rest at its equilibrium position when a force (P=80 N)... Pic a. .78 m/s b. .81 c. .71 d. .58 e. .64

A. .78m/s

A 0.04 kg ball is thrown from the top of a 30m tall building (A) at an unknown angle above horiz... KE? Pic a. 12 J b. -12 c. 20 d. -20 e. 32

A. 12 J

A skier weighing .80kN comes down a frictionless hiss run that is circ. (R=30m) at the bottom...Speed at B? Pic a. 17 m/s b. 19 c. 18 d. 20 e. 12

A. 17 m/s

A spring (k=600N/m) is at the bottom of a frictionless plane that makes an angle of 30deg with the horiz. Upper end depressed .10 mass=2kg...KE of block after traveling .1m? a. 2.0 J b. 1.8 c. 2.2 d. 1.6 e. 1

A. 2.0 J

A pendulum is made by letting a 2kg object swing at the end of a string that has a length of 1.5m. Max angle the string makes with vert. as pendulum swings is 30deg... a. 2.0 m/s b. 2.2 c. 2.5 d. 2.7 e. 3.1

A. 2.0 m/s

A 20kg mass is fastened to a spring (k=380N/m) that passes over pulley shown..Speed after mass dropped .40m? PIC a. 2.2 m/s b. 2.5 c. 1.9 d. 1.5 e. 3.6

A. 2.2 m/s

A 3kg block is on a frictionless horiz. surface. THe block is at rest when, at t=0... a. 2.3 W b. 2 W c. 1.4 W d. 1.7 W e. 1.2 W

A. 2.3 W

A 2kg block is projected down a plane that makes an angle of 20deg with the horiz with an initial Ke of 2 J... a. 3 m b. 1.8 c. .30 d. 1 e. 1.3

A. 3m

Objects A and B of mass M and 2M are pushed up a distance straight up an inclined plane by a force F parallel to the plane. At the highest point...

A. Ka> Kb.

As an objet moves from A to B only two forces act on it: one force is nonconservaitve does -30 J of work, the other conservative force does 50J of work. ..

A. The Ke of object increases, ME decreases.

A particle is acted upon by only two forces, one conservative and one nonconsertaive and neither being a force of friction...

A. The sum of the works of the two forces is zero.

The solution to a problem is the equation below. Which description best fits the solution?

A. Vertical spring compressed ,120 shoots a .2kg mass 2.90 cm above the equilibrium position.

any change of the energy of a system occurs because of...

A. energy transfer across the boundaries of the system.

A kg block slides down a plane (inclined 40deg with horiz) at 5.0m/s a. +98 W b. 63 c. zero d. 75 e. -75

B. +63 W

A 3kg mass is dropped from the edge of a 50m tall building with initial speed of zero... a. -4.6 kJ b. -.53 kJ c. -.61 kJ d. -.38 kJ e. -.81 kJ

B. -.53 kJ

A small lead sphere of mass m is hung from a spring of spring constant k... a. -kx^2 b. -.5kx^2 c. 0 d. .5kx^2 e. kx^2

B. -.5kx^2

A 10kg object is dropped from rest. After falling 50m its speed is 26m/s... a. -1.3 kJ b. -1.5 kJ c. -1.8 d. -2 e. -2.3

B. -1.5 kJ

A 6kg block slides along a horiz. surface. If Uk=.20 for the block and surface, what rate is the friction force changing the ME of the block when speed is 4 m/s? a. -59 W b. -47 c. -71 d. -82 e. 71

B. -47W

A 1kg block is release from rest at the top of a frictionless incline that makes an angle of 37deg with the horiz. How far does mass slide? a. .98 m b. .68 c. .82 d. .55 e. .20

B. .68

A 2kg mass is projected from the edge of the top of a 20m building with v=24m/s at some unknown angle above horiz. KE before it hits ground? a. .18 kJ b. .97 c. .89 d. .26 e. .4

B. .97 kJ

A .40kg particle moves under influence of a single conservative force at point. A point A where the particle has speed of 10m/s... a. 65 J b. 15 J c. 35 J d. 45 J e. -40 J

B. 15 J

A 2kg mass swings at the end of a string (length 3m) its speed at the lowest point on its circ. path is 6m/s... a. 21 J b. 15 c. 28 d. 36 e. 23

B. 15 J

A single conservative force Fx=(6.0-12) N acts on a particle moving along the x axis. What's the PE at x=3m a. 11 J b. 29 J c. 9 J d. -9 J e. 20 J

B. 29 J

A champion athlete can produce one horsepower (747 W) for a short period of time. If a 70kg athlete were to bicycle to the summit of a 500m high mountain while expending power at this rate, she would have used... a. 746 b. 3.43x10^5 c. 3.73x10^5 d. 7.46x10^5 e. 2.61x10^7

B. 3.32x10^5

A 2kg block sliding on a rough horizontal surface is attached to one end of a horiz. spring (k=250 N/m) which has its other end fixed... a. .32 b. .45 c. .58 d. .19 e. .26

B. 45

A champion athlete can produce one horsepower for a short period of time...she should reach the summit in ... a. 1 b. 460 c. 500 d. 1000 e. 35000

B. 460

A 3kg block is on a horizontal surface. Block is at rest when t=0...The CoKF between the block and surface is .20... a. 54 W b. 49 c. 44 d. 59 e. 24

B. 49 W

A .60 kg object is suspended from the ceiling at the end of a 2m string. When pulled and released, its speed =4m/s a. 61 degrees b. 54 c. 69 d. 77 e. 47

B. 54 degrees

A spring (k=600 n/M) is placed on a vertical position with its lower end supported by horz. surf. 2kg block is initially .40m above upper end...KE after falling .50m? a. 5.3 J b. 6.8 c. 6.3 d. 5.8 e. 6.5

B. 6.8 J

A block (m=4kg) sliding on a horiz. frictionless surface is attached to one end of a horiz. spring (k=100N/m)...Speed 16cm from equilibrium? a. 71 cm/s b. 60 c. 80 d. 87 e. 57

B. 60 cm/s

A spring (k=200N/m) is suspended with its upper end supported from ceiling. Mass 2kg...Speed of object after falling 4cm? a. 90 cm/s79 b. 79 c. 96 d. 83 e. 57

B. 79 cm/s

Two equal masses are raised at constant velocity by ropes that run over pulleys... PIC a. Fb=Fa;Pb=Pa b. Fb=Fa;Pb=2Pa c. Fb=2Fa;Pb=Pa d. Fb=2Fa; Pb=2Pa e. Pa=Fa; Pb=Fb

B. Fb=Fa; Pb=2Pa

Jane and Jake

B. Jane because work does not depend on mass, only on force times distance.

Two masses Ma and Mb with Mb=2Ma are released at the same time and allowed to fall staright down. We compare KE for equal TIMES... a. Kb=Ka b. Kb=2Ka c. Kb=4Ka d. Ka=2Kb e. Ka=4Kb

B. Kb=2Ka

Two masses, Ma and Mb with Mb=2Ma are released at the same time and allowed to fall straight down. We compare KE for equal distances... a. Kb=Ka b. Kb=2Ka c. Kb=4Ka d. Ka=2Kb e. Ka=4Kb

B. Kb=2Ka

As an object moves from A to B two forces act on it. conservative =-70. nonconservative = 5-J. Between A and B.

B. The KE of object decreases, ME increases.

As a result of friction between internal parts of an isolated system...

B. The total ME of the system decreases.

A 2kg block slides down a fixed rough curved track, Block has speed of 5m/s... a. -14 J b. -12 c. -10 d. -16 e. -25

C. -10 J

A 1.6 kg block slides down a plane (inclined 25deg) with horiz at a constant speed of 2.0 m/s. At what rate is the frictional force changing the ME of the block? a. 28 W b. 13 W c. -13 W d. -28 W e. 6.5 W

C. -13 W

As a particle moves along the x axis it is acted upon by a single conservative force given by Fx = (20-4x) N Value of PE at 4.0m? a. -48 J b. 78 J c. -18 J d. 48 J e. 80 J

C. -18 J

A 25 kg block on a horizontal surface is attached to a spring (Fconstant= 8kN/m). The block is pulled 10cm to the right from its equilibrium position... a. -4 J b. -3.5 c. -2.4 d. -2.9 e. -15

C. -2.4 J

At what rate is the gravitational force on the 2kg projectile doing work at an instant when the velocity of the projectile is 4m/s directed 30deg above horiz.? a. 39 W b. -78 c. -39 d. 78 e. 25

C. -39 W

A 1.2 kg mass is projected up a rough circular track (r=.8m) as shown. Speed at A is 8.4 m/s, B is 5.6 m/s. PIC a. -2.7 J b. -8.8 c. -4.7 d. -5.7 e. -19

C. -4.7 J

A .75kg sphere is released from rest and is moving 5m/s after falling 2m in a viscous medium... a. -6.1 J b. -4.6 c. -5.3 d. -6.8 e. -2.7

C. -5.3 J

1.2kg mass is projected down a rough circular track (R=2m) as shown. Speed of mass at A is 3.2, B 6m/s... PIC a. -8.9 J b. -7.3 c. -8.1 d. -6.6 e. -24

C. -8.1 J

In a given frictionless displacement of a particle, its KE increases by 25 J while its PE decerase by 10 J... a. -15 b. 35 c. 15 d. -35 e. 55

C. 15 J

A .80kg object tied at the end of 2m string swings as a pendulum. At lowest point, KE is 10 J... a. 5.6 m/s b. 4.4 c. 3.3 d. 5 e. 6.1

C. 3.3 m/s

A 2kg block sliding on a horizontal frictionless surface is attached to one end of a horizontal k=200N/m... Speed 20cm from equilibrium? a. 2.6 m/s b. 3.1 c. 3.5 d. 1.9 e. 2.3

C. 3.5 m/s

An all terrain vehicle of 2000kg mass moves up a 15deg slop at 6m/s... a. 5.25 kW b. 24.8 c. 30.4 d. 118 kW e. 439 kW

C. 30.4 kW

A 3.5 kg block is pulled along a moving conveyor belt at a constant speed of .500 m/s relative to a stationary observer ... a. 5.6 b. 22.0 c. 32.9 d. 54.8 e. 76.8

C. 32.9

A 2.5 kg object suspended from the ceiling by a string that has a length of 2.5m is released from rest with the string 40deg below the horiz. position. a. 11 N b. 25 c. 42 d. 18 e. 32

C. 42 N

A skier weighing .70 kN goes over a frictionless hill as shown...Speed at B? Pic a. 3.1 m/s b. 6.2 c. 5.2 d. 4.1 e. 6.5

C. 5.2 m/s

A 7kg block on a horizontal frictionless surface is attached to light spring (Fconstant 1.2 kN/m). Pic a. 7.4 J b. 5.4 J c. 6.1 J d. 6.7 J e. 4.9 J

C. 6.1 J

The block shown is released from rest when the spring is stretched a distance d. If K=50N/m... a. 92 cm/s b. 61 c. 71 d. 82 e. 53

C. 71 cm/s

Cubical blocks of mass m and side l are piled on a vertical column, The total GPE of a colum of three blocks is... a. 5/2mgl b. 3 c. 9/2 d. 6 e. 9

C. 9/2mgl

As a 1kg object moves from point A to point B, it's acted upon by a single conservative force which does -40 J of work... a. 72 J b. 10 c. 90 d. 29 e. 68

C. 90 J

Identicall masses m are attached to identical springs of spring constant k suspended form the ceiling...

C. Masses A and B will travel equal distances between their highest and lowest points.

A spring with spring constant 800N/m compressed .200 is released and projects .800...The following student solution contains at least one error..

C. The EPE is equal to either the KE or the internal thermal.

A pendulum bob... Pic a. Uo=Ua=Ub b. Ua-Ub=2Uo c. Ua-Ub=Uo-Ua d. Uo=Ub=2Ua e. Uo-Ua=2(Ua-Ub)

C. Ua-Ub = Uo-Ua

The same force F is applied horizontally to bodies 1,2,3,4...

C. V1=sq(2)v2=sq(3)v3=2v4

A large spring is used to stop the cars after they come down the last hill of a roller coaster... PIC a. XA = 1/2Xb b. =XB c. = sq(2)XB d. = 2Xb e. = 4Xb

C. XA = sq(2)Xb

A 12kg projectile is launched with an initial vertical speed of 20m/s. It rises to a max height of 18m... a. -.64 kJ b. -.4 c. -.52 d. -.28 e. -.76

D. -.28 kJ

The two masses in the figure are released from rest. After the 3kg mass has fallen 1.5m, it's movig with a speed of 3.8 m/s a. -12 J b. -17 c. -20 d. -8 J e. -28 J

D. -8 J

A spring with spring constant k=800N/m is compressed 12 cm from its equilibrium... a. .060m b. .085 c. .12 d. .17 e. .24

D. .17m

The equation below describes a physical situation...

D. 1.70kg block speeds up while sliding down a plane with Uk=.320 with the plane inclined at 30deg.

Starting from rest at t=0, a 5kg block is pulled across a horiz. surface by a constant horiz. force having a magn. of 12 N. a. .13 kW b. .14 c. .12 d. 26 e. 12

D. 26 W

A spring (k=600N/m) is placed in a vert. position with its lower end uspported by a horiz. surface...How far will block rise? a. 46cm b. 36 c. 41 d. 31 e. 20

D. 31 cm

A certain pendulum consists of a 1.5kg mass swinging at the end of a string (length 2m). At lowest point, tension is 20 N... a. 77 cm b. 50 c. 63 d. 36 e. 95

D. 36 cm

A champion athlete can produce one horsepower for a short period of time. The number of 16 cm high steps a ... a. 4 b. 7 c. 65 d. 408 e. 4567

D. 408

Which of the following is a conservative force?

D. Grav. force acting on car.

The speed of a 4kg object is given by v=2t m/s... a. 48 W b. 40 c. 32 d. 56 e. 16

E. 16 W

A spring with constant k=800N/m is extended 12 cm from equilibrium. A pring with 6cm extension from equil... a. 200 N/m b. 400 c. 800 d. 1600 e. 3200

E. 3200 N/m

A 3.5 kg block is pulled along a moving conveyor belt at a constant speed of .500 m/s relative to stationary observer....OPPOSITE DIRECTION... a. 5.6 b. 22 c. 32.9 d. 54.8 e. 76.8

E. 76.8

An astronaut tosses a ball out in space where gravitational forces may be neglected. What will happen to the ball?

E. It will be sowed down very gradually by collisions with molecules in space.

Object A and B of mass M and 2M are each pushed a distance d straight up an inclined...

E. Long equation

The force a spring exerts on a body is a conservative force because...

E. The net work a spring does on a body is zero when the body returns to its initial position.

For a force to be conservative force, when applied to a single test body...

E. no net work must be done for motion in closed paths.