FINAL LAB EXAM PHYS 125L

This picture is taken from the Modified Atwood's Machine in the Pivot Interactives (Lab#4*). The system mass is M = 400 g, the hanging mass is m = 20 g, the vertical distance that the hanging mass drops is y = 0.45 m (45 cm), and the time it takes is t = 1.46 s. Take acceleration due to gravity as 9.80 m/s2.

(a) 0.422 m/s2 (b) 0.467 m/s2 (c) 10.1 %

A 416 - gram sample of a metal is heated from 22 oC to 173 oC. The quantity of heat absorbed by the metal 1,695 J. What is the specific heat of the metal in J/goC? Please give your answer in three decimal places.

0.027

The following data were taken with the Modified Atwood's machine (Lab#4*) The time shown in the table below is the time the hanging mass moves through a vertical distance y = 0.88 m which is fixed. Use the data in the table below to calculate the average acceleration in m/s2. Please round your answer to two decimal places.

0.112

An Mm = 34 grams sample of a metallic cylinder is heated to a temperature of Tm = 92 oC. It is placed in Mw = 128 grams of water in a calorimeter cup with a specific heat of ccal = 0.121 cal/g Co. The mass of the calorimeter cup is Mcal = 47.1 grams. The initial temperature of the water and calorimeter cup is To = 20.4 oC. The final equilibrium temperature of the system is Te = 23.7 oC. What is the specific heat of the metallic cylinder, cm? The specific heat of water is cw = 1.0 cal/g Co. Please round your answer to three decimal places.

0.19

The mass of a steel cylinder is 699.6 grams (g). What is its mass in kilograms (kg)? Please round your answer to two decimal places.

0.7

If the period of a simple pendulum on earth is 1.7 seconds, what is its length? Take the acceleration due to gravity,g, as 9.80 m/s2. Please round your answer to two decimal places. Equation: Use this equation and solve for 𝐿L 𝑇=2𝜋𝐿𝑔‾‾√

0.72

Suppose that, in Lab # 2, you repeated three measurements for time as t1 = 0.774 s, t2 = 0.794 s, and t3 = 0.783 s. What is the average time, tav ? (Unit of time is second, s. Please round your answer in three decimal places).

0.784

Suppose that, in Lab # 4, you measured the height of the air track as h = 14 cm and the distance along the ramp is d = 169 cm. What is the acceleration of the dry ice puck in m/s2. Use acceleration due to gravity to g = 9.80 m/s2). Please round your answer to three decimal places.

0.812

Suppose that, in Lab#2, you measured the average acceleration to be 0.42 in m/s2 when the distance,in meters, is 0.92. What is the speed of the dry ice puck in m/s? Please round your answer to three decimal places. Use this equation to find the speed: 𝑣=2𝑎𝑑‾‾‾‾‾√v=2ad

0.879

In the figure shown below, mass m1 = 100 grams, m2 = 300 grams, and m3 = 100 grams. What is the absolute percent difference between the clockwise and counterclockwise torques if the system is in equilibrium? Assume that the meter stick is uniform and symmetric.

1.74 %

Write the product 32695.00 x 57.00 in scientific notation with the correct significant figure.

1.864 x 106

The figure shown below is a uniform meter stick where the fulcrum (pivot) is at the 24-cm mark when a mass m1 = 201 grams is attached to the meter stick at the 10-cm mark. The center of gravity of the meter stick is the 50-cm mark. What is the mass of the meter stick, in grams, if the system is in rotational equilibrium? Please round your answer to one decimal place.

108.2

The figure shown below comes from Pivot Interactives Lab#7 (Measuring Torque). If the attached mass (on the right) is M = 3.81 kg, what is the magnitude of the torque due to the attached weight? You have to read the perpendicular distance, 𝑟r, from the ruler. Take the acceleration due to gravity, g, as 9.80 m/s2. Please round your answer to one decimal place.

12.8

A ball is launched as a projectile at an angle of 21o. The initial velocity of the ball is 42 m/s. What is the maximum horizontal distance, in meters, that the ball reaches? Take the acceleration due to gravity, 𝑔g, to be 9.80 m/s2. Please round your answer to the nearest whole number. Equation: range, R = 𝑣2𝑜sin(2𝜃)𝑔

120

A temperature reading of TC = 57 oC is equivalent to how many degrees on the Fahrenheit scale, TF? Please round your number to the nearest whole number (integer). Equation: 𝑇𝐹=(95𝑇𝐶)+32

135

A projectile is launched from the ground level at an angle of 50o and with an initial velocity of 32 m/s. What is the vertical component of the projectile's velocity at t = 1.06 s? Please note that your answer may be negative. If this is the case, put the negative answer in the box. Please round your answer to one decimal place.

14.1

A football is kicked from the ground level at an angle of 26o and with an initial velocity of 43 m/s. How high (in meters) does the ball reach in t = 1.66 s? Please round your answer to one decimal place. Equation: y = voy t + (1212) ay t 2 where ay = - 9.8 m/s2 and voy = vo sin 𝜃θ.

17.8

A dry ice puck (similar to the one in Lab#6*) is measured to be sliding (moving) at a speed of 6.7 m/s just before it compresses the double spring. The puck completely compresses the spring and comes to a stop. The mass of the puck is 0.33-kg. What is the spring constant, 𝑘k ( in N/m) if the maximum spring compression is Δ𝑥Δx = 0.078 m? Please round your answer to the nearest whole number (integer). Equation: 12𝑚𝑣2=12𝑘(Δ𝑥)212mv2=12k(Δx)2

2,435

A simple pendulum is timed as it swings back and forth. The clock is started when the bob is at the left end of its swing. When the bob returns to the left end for the 30th return, the clock reads 60.0s. What is the period of the simple pendulum?

2.00 s

The figure below shows a vernier caliper scale set to a particular reading. What is the reading of the scale?

2.22

The length of a metallic cylinder is 11.29 cm. What is the volume of the cylinder, in cm3, if the radius of the cylinder is measured to be 2.44 cm? Please round your answer to two decimal places.

211.17

A simple pendulum here on earth has a period of 9.3 s. What would be its period on the moon where the acceleration due to gravity is 1.63 m/s2 ? Take the acceleration due to gravity on earth,g, as 9.80 m/s2. Please round your answer to one decimal place.

22.8

What is the torque of a 26 N force that acts perpendicularly,𝐹⊥F⊥, at a point that is 𝑟r = 1 m from the fixed point (pivot) of a long horizontal stick? Give your answer as whole number (integer). The SI unit of torque is N.m. Equation: Magnitude of torque, 𝜏=𝑟𝐹⊥

26

What is the period of motion of a simple pendulum (on earth) when the string length is 2.5 m? Take the acceleration due to gravity,g, as 9.80 m/s2. Please round your answer to one decimal place. Equation: The period, 𝑇=2𝜋𝐿𝑔‾‾√T=2πLg

3.2

Suppose that, in performing Lab#5*, you measured the acceleration due to gravity to be 9.47 m/s2. What is the absolute percent error (in three significant figures) in the acceleration if the accepted value is 9.81 m/s2.

3.47 %

Suppose that, in Lab # 2, you measured the average time for 1.66 meters along the ramp as 0.89 seconds. What is the velocity of the dry ice puck in m/s. Please round your answer to three decimal places. Use this equation: 𝑣=2𝑑𝑡v=2dt

3.73

Suppose you mix m1 = 21 grams of hot water at T1 = 90 oC with m2 = 97 grams of water at T2 = 20 oC. What would be the final equilibrium temperature, Te , of the mixture. The specific heat water is 𝑐c = 4.18 J/g oC. Please round your answer to one decimal place.

32.5

For the meter stick shown in the figure shown below, the force F1 is unknown and it acts at the 10- cm mark. F1 is balanced by another force, F2 = 70 N that acts at the 70-cm mark. What is the magnitude F1 ,in Newtons, about an axis through the point B? Please round your answer to one decimal place.

35

The standard specific heat of a certain metallic cylinder is cs = 0.24 cal/g Co. You conducted a calorimetric experiment and you found that the specific heat of the metallic cylinder is ce = 0.25 cal/g Co. What is the percent error of your experiment? If your answer is negative, put the negative number in the answer box. Please round your answer to two decimal places. Equation: % Error = (𝑐𝑒−𝑐𝑠)𝑐𝑠×100

4.17

A net force of 34 N acts on a 8 kg object. What is the acceleration of the object in m/s2? Please round your answer to one decimal place.

4.3

In the figures shown below (Atwood's Machine), m1 = 0.8 kg and m2 = 2.1 kg. What is the acceleration of the system in m/s2? Take the acceleration due to gravity, g = 9.8 m/s2.

4.4

A 34 kg mass is pulled up by means of a rope. The mass accelerates upward at 2.8 m/s2. What is the tension (tightness) in the rope in newtons? Take the acceleration due to gravity, g = 9.8 m/s2. Please round your answer to one decimal place.

428.4

An event on the moon (where acceleration due to gravity is 1.63 m/s2) took 149 minutes (according to a simple pendulum-based clock). How long (in minutes) would the same event take on earth (based on the same pendulum-based clock)? Acceleration due to gravity on earth is 9.80 m/s2. Please round your answer to the nearest whole number (integer).

61

A simple pendulum, whose period on earth is 3.46 s, is transported to an unknown planet where its period is found to be 1.36 s. What is the acceleration due to gravity on this unknown planet in m/s2? Take the acceleration due to gravity on earth,g, as 9.80 m/s2. Please round your answer to one decimal place.

63.4

A series of four measurements of the mass, length, and diameter of a cylinder are made by a student. The results of these measurements are: Mass, M (g)Length, L (cm)Diameter, D (cm)Density, 𝜌ρ (g/cm3)20.62.681.1120.42.671.0720.82.651.0619.92.611.08 What are (a) the standard deviation of the density, and (b) the standard error of the density? Please express your answer in three significant figures. Use this equation to calculate each density: 𝜌=4𝑀𝜋𝑑2𝐿ρ=4Mπd2L and then use MS Excel to find the standard density, 𝜎σ, and the standard error, 𝛼

7(a) standard deviation, 𝜎σ = 0.395 g/cm3 and (b) standard error, 𝛼α = 0.197 g/cm3

A golf ball is launched from the ground level at an angle of 61o and with an initial velocity of vo = 42 m/s. What is the time of flight, t, of the ball (i.e., total time that the ball is in the air)? Ignore the effect of air resistance. Please round your answer to one decimal place.

7.5

Suppose that you put 28.6 gallons of gasoline in your car tank. How many kilograms of gasoline did you put in your tank? Take the density of gasoline as 721 kg/m3 and 1.0 gallon = 0.00378 m3. Please round your answer to the nearest whole number (integer).

78

A sample of water with a mass of 39 grams is heated from 25 oC to 80 oC. How much heat, in Joules, did the sample absorb? The specific heat of water is 𝑐c = 4.182 J/goC. Please round your answer to the nearest whole number (integer). Equation: 𝑄=𝑚𝑐Δ𝑇Q=mcΔT Δ𝑇ΔT is the change in temperature.

8,970

The figures shown below are from Lab#1 (Density of Metals). What is the approximate density of the metal that is shown (all three figures are for the same metal).

8.35 g/cm3

A cylinder has a length of 4.31 cm, a diameter of 1.536 cm, and a mass of 71 grams. What is the density of the cylinder in g/cm3? Please round your answer to one decimal place.

8.9

The period of a simple pendulum is 2 s. If you want to triple the period (6s), what length string will you need?

9.0 m

The dry ice puck in Lab#6* compresses the double spring (with a spring constant of 350 N/m). The elastic energy that the compressed spring has is E = 165 J. What is the maximum compression of the spring, in cm, from its relaxed position? Please round your answer to the nearest whole number (integer). Equation: 𝐸=12𝑘(Δ𝑥)2E=12k(Δx)2 Then convert Δ𝑥Δx into cm by multiplying the answer by 100.

97

The table below shows time, temperature, and temperature change data collected using Pivot Lab#8 (Specific Heat of Water Experiments). The heat supplied, Q, is to be calculated from Q = Pt (where P is the power of the light bulb which is 15 watts and t is the time). For example, when t = 200 s, Q = 15 watts x 200 s = 3000 Joules. Plot Temp. Change (vertical axis) versus Heat Supplied (horizontal axis) and find the slope (use MS Excel). Then calculate the specific heat, 𝑐c, from 𝑐=1𝑠𝑙𝑜𝑝𝑒×𝑚𝑎𝑠𝑠c=1slope×mass. The mass of the water is 925 grams = 0.925 kg. What is the specific heat of water, 𝑐c, according to the data? Please make sure that your slope is in three significant figures (from Excel)

= 4413 J/kg oC

In the Pivot Interactives Lab#8 (Specific Heat of Water Experiments), you will notice a discrepancy between the calculated and the standard specific heats of water. One or more of the following reasons could cause this discrepancy: A. Light energy is escaping from the beaker, so it is not heating the water. This means that the energy heating the water is less than the total energy coming from the bulb. B. The beaker is not insulated so heat energy escapes from the beaker. C. The actual power of the light bulb is less than what the label says (15 watts) D. The beaker itself absorbs some of the heat.

All of the above

In the figure shown below, the fulcrum (pivot) is at the 0.40-m mark. The masses are placed at the following locations: m1 = 0.10 kg at 0.05 m; m2 = 0.20 kg at 0.20 m; m3 = 0.5 kg at 0.70 m; and m4 = 0.30 kg at an unknown position. With the meter stick supported at the 0.40-m mark, what is the position at which mass m4 balances the meter stick? The mass of the meter stick mo = 0.150 kg. Take the center of gravity to be at the 0.50-m mark.

At the 0.10-m mark

The figure shown below is taken from a PheT projectile simulation lab. How would you best describe the two curves A (the blue curve) and B (the purple curve)?

Both curves are due to projectiles launched with the same velocity. However, projectile A is launched without air resistance and projectile B is launched with air resistance.

If a spaceship takes a simple pendulum to Saturn (g=11.2 m/s2), the period of the pendulum on Saturn compared to that on Earth will

Decrease

A pan made of which substance would require the smallest amount of heat for equal cooking?

Gold ( c = 0.03 cal/gCo)

Suppose that you are give a choice of which spring and which mass to use in order to produce the maximum compression Δ𝑥Δx. Spring A has spring constant 250 N/m Spring B has spring constant 390 N/m Mass C is 0.60 kg Mass D is 1.50 kg. Which mass would you put on top of which spring to produce the maximum compression Δ𝑥Δx? Hint: Look at Hooke's Law 𝐹=𝑘Δ𝑥F=kΔx where 𝐹=𝑚𝑔F=mg

Put Mass D on top of Spring A.

If the mass of the simple pendulum bob (the mass of the hanging ball) is doubled, the period of the pendulum will

Remain the same

The table blow shows the data from Modified Atwood's Machine (Lab#4*) for y= 0.42 m (42 cm) and various different hanging masses (the system mass is fixed at M = 400 g). What is the slope of the graph of acceleration (vertical axis) versus force (horizontal axis)?

Slope = 2.30 kg-1

Why is it necessary or important to use dry ice for Lab#2 virtual experiment?

The dry ice minimizes force of friction.

The Figure shown below is taken from Lab#2 (Graphing the Motion of a Dry Ice Puck on a Ramp). What is the approximate position of the puck, in cm, at t = 0.5000 s? The position of the puck is where the center of the puck (the small black dot) is.

The position of the puck is at 56 cm.

A baseball is launched from an angle and travels along a parabolic arc (projectile motion without air resistance) before it strikes the ground. Which one of the following statements is TRUE?

The x-component of the velocity of the ball is constant throughout the ball's flight.

The carts shown below are all moving in a straight line to the right. The pictures were taken 1.00 s apart. Which picture shows a cart that is moving at a positive acceleration?

a

If m1 and m2 (in the Atwood machine in the previous question) are equal, then the acceleration of the system will be:

a=0

The carts shown below are all moving in a straight line to the right. The pictures were taken 1.00 s apart. Which picture shows a cart that is moving at constant velocity?

b

Which of the following graphs of velocity versus time represent a constant acceleration motion?

b

The density of a metal depends on the shape of the metal. Is this statement true or false?

false

What force is responsible for moving the dry ice puck down the ramp?

force of gravity

For a stone moving as a projectile in 2-dimensional space, the horizontal component of the acceleration of the stone (assume that are resistance is negligible).

is zero

In the Atwood machine shown below, the acceleration of the system is found to be 4.2 m/s2. Which combination of m1 and m2 is possible for this acceleration?

m1 = 20 kg and m2 = 50 kg

Suppose you hold a 12-cm3 block of aluminum (whose density is 2.70 g/cm3) and a 2.0-cm3 block of brass (whose density is 8.40 g/cm3) in your two hands. Which block has more mass?

the block of aluminum has more mass

One of the following is a condition for the rotational equilibrium of a rigid body:

the clockwise and the counter clockwise torques have to be equal in magnitude.

The figures shown below are from Lab#6*. What is the maximum compression of the double spring, Δ𝑥Δx, caused by the weight placed on top of the spring? The maximum compression is the difference between the length of the relaxed spring (in its equilibrium position as seen from the figure on the left) and the length of the compressed spring (as seen from the figure on the right).

Δ𝑥 = 2.2 cm

The figures shown below are from Lab#6*. What is the maximum compression of the double spring, Δ𝑥Δx, of the dry ice puck (measured along the inclined plane)? The maximum compression is the difference between the length of the relaxed spring (in its equilibrium position as seen from the figure at the top) and the length of the completely compressed spring (as seen from the figure at the bottom).

Δ𝑥 = 4.50 cm

The figure shown below is from Lab#6*. What is the height, Δ𝑦Δy, of the dry ice puck (measured from the baseline to the center of the puck)?

Δ𝑦 = 15 cm

In Part 2 of Lab#6*, a 0.50-kg mass is placed on top of the double spring. The spring is compressed by Δ𝑥Δx = 2.65 cm (0.0265 m). What is spring constant, 𝑘k? Equation: Use Hooke's Law 𝐹=𝑘Δ𝑥F=kΔx where 𝐹=𝑚𝑔F=mg (𝑔g = 9.80 m/s2)

𝑘 = 185 N/m