phy 101 exam 3

c) Q<0

a cylinder of fas has a frictionless but tightly sealed piston of mass M. small masses are placed onto the top causing it to slowly move downward. a water bath keeps the temperature constant. in this process (SEE GRAPH SHEET #5) a) Q>0 b) there is not enough information to say anything about the heat c) Q<0 d) Q=0

a) 6.25 rad/s

a figure skater rotating at 5.00 rad/s with arms extended has a moment of inertia of 2.25 kgxm2. if he pulls in his arms so his moment of inertia decreases to 1.80 kgxm2, what will be his new angular speed? a) 6.25 rad/s b) 4.60 rad/s c) 2.25 rad/s d) 0.81 rad/s

b) 2900

a person running in place on an exercise machine for 10 min uses up 17 kcal (food calories). another person exercises by repeatedly lifting a 5 kg weights a distance of 50 cm. how many repetitions of this exercise are equivalent to 10 minutes of running in place? assume that the person uses negligible energy in letting down the weights after each lift. (1 cal = 4.186 J) a) 1450 b) 2900 c) 730 d) 2200 e) 1500

b) the rubber ball

a rubber ball and a lump of clay have equal mass. they are thrown with equal speed against a wall. the ball bounces back with nearly the same speed with which it hit. they clay sticks to the wall. which one of these objects has the greater momentum change? a) the clay b) the rubber ball c) both of them have the same non-zero momentum change d) both of them have zero momentum change

e) all have the same speed

a small child slides down the four frictionless slides A-D. which slide will result in the child having the fastest speed at the bottom of the slide? (SEE GRPAH SHEET #4) a) A b) B c) C d) D e) all have the same speed

a) her angular momentum remains almost constant

a spinning ice skater is able to control the rate at which she rotates by pulling in her arms. which of the following statement are true about the skater during this process? a) her angular momentum remains almost constant b) her kinetic energy remains almost constant c) she is subject to a constant non-zero torque d) her moment of inertia remains almost constant

c) Kt = (16)Kc

a truck has four times the mass of a car and is moving with twice the speed of the car. if Kt and Kc refer to the kinetic energies of truck and car respectively, it is correct to say a) Kt = (4)Kc b) Kt = (1/2)Kc c) Kt = (16)Kc d) Kt = Kc e) Kt = (2)Kc

c) 20 m

an object with a mass of 10 kg is initially at rest at the top of a frictionless inclines plane that rises at 30 degrees above the horizontal. at the top, the object is initially 8.0 m from the bottom of the incline, as shown in the figure. when the object is released from this position, it eventually stops at a distance d from the bottom of the inclined plane along a horizontal surface, as show. the coefficient of kinetic friction between the horizontal surface and the object is 0.20, and air resistance is negligible. find the distance d. (SEE GRPAH SHEET #6) a) 15 m b) 5.0 m c) 20 m d) 10 m e) 25 m

d) 1300 kcal

at room temperature, a typical person loses energy to the surroundings at the rate of 62 W. if this energy loss has to be made up by an equivalent food intake, how many kilocalories (food calories) does this person need to consume everyday just to make up this heat loss? a) 1100 kcal b) 1500 kcal c) 1000 kcal d) 1300 kcal e) 1600 kcal

d) 126 J

during each cycle of operation, a refrigerator absorbs 230J of heat from the freezer and expels 356 J of heat to the room. how much work input is required in each cycle? a) 460 J b) 586 J c) 712 J d) 126 J

b) B

each of the 1.0 kg boxes starts at rest and is then pulled for 2.0 m across a level, frictionless floor by a rope with the noted force at the noted angle. which box has the highest final speed? (SEE GRAPH SHEET #2) a) A b) B c) c d) D e) E

d) 95 J

how much work would a child do while pulling a 12 kg wagon a distance of 4.3 m with a 22 N force? a) 67 J b) 109 J c) 52 J d) 95 J

b) 5.7 cm

if 4.0 J of work are performed in stretching an ideal spring with a spring constant (force constant) of 2500 N/m, by what distance is the spring stretched? a) 0.3 cm b) 5.7 cm c) 3.2 m d) 3.2 cm e) 5.7 m

a) four times jack's power output

jill does twice as much work as jack does and in half the time. jill's power output is a) four times jack's power output b) the same as jack's power output c) one-half as much as jack's power output d) one-fourth as much as jack's power output e) twice jack's power output

b) 0.40

the efficiency of this heat engine is (SEE GRAPH SHEET #1) a) 0.20 b) 0.40 c) 0.60 d) 0.66 e) 1.00

e) -75 kgxm/s

the graph in the figure shows the x component F of the net force that acts for 10 s on a 100 kg crate. what is the change in momentum of the crate during the 10 s that this force acts? (SEE GRPAH SHEET #3) a) 75 kgxm/s b) -25 kgxm/s c) 25 kgxm/s d) -100 kgxm/s e) -75 kgxm/s

c) 0.047 m/s toward the right

two air track cars move along an air track towards each other. cart A has a mass of 450 g and moves toward the right with a speed of 0.850 m/s. cart B has a mass of 300 g and moves toward the left with a speed of 1.12 m/s. what is the total momentum of the two-cart system? a) 0.719 kgxm/s toward the right b) 0.750 kgxm/s toward the right c) 0.047 kgxm/s toward the right d) 0.719 kgxm/s toward the left e) 0.750 kgxm/s toward the left

a) 26 kxm/s

two dogs, Rover and Fido, run on a level frictionless surface. Rover runs eastward with a momentum of 24 kgxm/s, and Fido runs northward with momentum 10 kgxm/s. they make a sudden perfectly inelastic collusion. what is the magnitude of their combined momentum after the collision? a) 26 kgxm/s b) 34 kgxm/s c) 14 kgxm/s d) it cannot be determined without knowing the masses and velocities of the dogs

e) 0.28 m/s

two ice skaters suddenly push off against one another starting from a stationary position. the 45 kg skater acquires a speed of 0.375 m/s relative to the ice. what does the 60 kg skater acquire relative to the ice? a) 0.75 m/s b) 0.38 m/s c) 0.00 m/s d) 0.50 m/s e) 0.28 m/s

d) 0.350 J

what is the kinetic energy of a 120 cm thin uniform rod with a mass of 450 g that is rotating about its center at 3.60 rad/s? a) 0.700 J b) 2.10 J c) 4.20 J d) 0.350 J e) 0.960 J