PHYS 101 Ivy Tech Rakesh K Shah All Homework Questions

The following exact conversion equivalents are given: 1 m = 100 cm , 1 in = 2.54 cm, and If a computer screen has an area of 1.27 ft2, this area is closest to

0.118 m2.

To determine the location of the center of mass (or center of gravity) of a car, the car is driven over a scale on a horizontal floor. When the front wheels are over the scale, the weight recorded by the scale is 5800 N, and when the rear wheels are over the scale, the scale reads 6500 N. The distance between the front and rear wheels is measured to be 3.20 m. How far behind the front wheels is the center of mass located?

1.69 m

A fire hose is turned on the door of a burning building in order to knock the door down. This requires a force of 1000 N. If the hose delivers 40 kg of water per second, what is the minimum velocity of the stream needed to knock down the door, assuming the water doesn't bounce back?

25 m/s

In the number 0.00723, the number of significant figures is.

3

The absolute temperature of a gas is T. In order to double the rms speed of its molecules, what should be the new absolute temperature?

4T

Two planets have the same surface gravity, but planet B has twice the radius of planet A. If planet A has mass m, what is the mass of planet B?

4m

A solid uniform sphere of mass 120 kg and radius 1.7 m starts from rest and rolls without slipping down an inclined plane of vertical height 5.3 m. What is the angular speed of the sphere at the bottom of the inclined plane?

5.1 rad/s

How long does it take for a rotating object to speed up from 15.0 rad/s to 33.3 rad/s if it has a uniform angular acceleration of 3.45 rad/s2?

5.30 s

The coefficient of linear expansion for aluminum is 1.8 × 10-6 K-1. What is its coefficient of volume expansion?

5.4 × 10^-6 K^-1

A hoop with a mass of 2.75 kg is rolling without slipping along a horizontal surface with a speed of 4.5 m/s when it starts down a ramp that makes an angle of 25° below the horizontal. What is the forward speed of the hoop after it has rolled 3.0 m down as measured along the surface of the ramp?

5.7 m/s

Vector A has magnitude 2 units and is directed to the north. Vector B has magnitude 5 units and is directed to the south. Calculate the magnitude and direction of A - B

7 units, north

A laser is thrown upward with a speed of 12 m/s on the surface of planet X where the acceleration due to gravity is 1.5 m/s2 and there is no atmosphere. How long does it take for the laser to reach the maximum height?

8.0 s

In a carnival ride, passengers stand with their backs against the wall of a cylinder. The cylinder is set into rotation and the floor is lowered away from the passengers, but they remain stuck against the wall of the cylinder. For a cylinder with a 2.0-m radius, what is the minimum speed that the passengers can have so they do not fall if the coefficient of static friction between the passengers and the wall is 0.25?

8.9 m/s

A window glass that is 0.5 cm thick has dimensions of 3 m by 1.5 m. The thermal conductivity of this glass is 0.8 W/m K. If the outside surface of the glass is at -10°C and the inside surface is at 20°C, how much heat flows through the window in every hour?

80 MJ

If a vector has components Ax < 0, and Ay > 0, then the angle that this vector makes with the positive x-axis must be in the range

90° to 180°

A 2294-kg sample of water at 0° C is cooled to and freezes in the process. How much heat is liberated? For water LF = 334,000 J/kg and LV = 2.256 × 106 J/kg. The specific heat of ice is 2050 J/kg K.

935,000 kJ

You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You have two choices about what to do with the ball: either catch the ball or deflect it back toward your friend with the same speed as it was originally thrown. Which choice should you make in order to maximize your speed on the skateboard?

Deflect the ball back.

If the sum of the external torques on an object is zero, then the sum of the external forces on it must also be zero.

False

The coefficient of linear expansion of copper is 17 × 10-6 K-1. A sheet of copper has a round hole with a radius of 3.0 m cut out of it. If the sheet is heated and undergoes a change in temperature of 80 K, what is the change in the radius of the hole?

It increases by 4.1 mm.

A thermally isolated system is made up of a hot piece of aluminum and a cold piece of copper, with the aluminum and the copper in thermal contact. The specific heat capacity of aluminum is more than double that of copper. Which object experiences the greater temperature change during the time the system takes to reach thermal equilibrium?

It is impossible to tell without knowing the masses.

Two solid spheres are made from the same material, but one has twice the diameter of the other. Which sphere will have the greater bulk modulus?

It will be the same for both spheres.

You slam on the brakes of your car in a panic, and skid a certain distance on a straight level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?

It would have skidded 4 times farther.

A firecracker explodes in midair and breaks up into many fragments. Which of the following statements are true regarding conditions immediately before and immediately after the explosion: I. The total momentum of the fragments is equal to the original momentum of the firecracker. II. The total kinetic energy of the fragments is equal to the original kinetic energy of the firecracker.

Statement I only

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct?

The acceleration is toward the east.

When adding 350 to 0.23

The answer would be 350.

A heavy sled and a light sled, both moving horizontally with the same speed, suddenly slide onto a rough patch of snow and eventually come to a stop. The coefficient of kinetic friction between the sleds and the rough snow is the same for both of them. Which of the following statements about these sleds are correct? (There could be more than one correct choice.)

The friction from the snow will do more negative work on the heavy sled than on the light sled. Both sleds will slide the same distance on the rough snow before stopping.

Satellite A has twice the mass of satellite B, and moves at the same orbital distance from Earth as satellite B. Compare the speeds of the two satellites.

The speed of B is equal to the speed of A.

The motions of a car and a truck along a straight road are represented by the velocity-time graphs in the figure. The two vehicles are initially alongside each other at time t = 0. At time T, what is true of the distances traveled by the vehicles since time t = 0?

The truck will have travelled further than the car.

You throw a baseball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down.

The work is negative on the way up and positive on the way down.

In an air-free chamber, a pebble is thrown horizontally, and at the same instant a second pebble is dropped from the same height. Compare the times of fall of the two pebbles.

They hit at the same time.

The graph in the figure shows the tensile stress as a function of the tensile strain in a certain wire. What does the slope of this graph give us for this wire?

Young's modulus for the material of the wire

If a tree is 15 m tall, its height expressed in feet is x ft, where x is

greater than 15.

The position x, in meters, of an object is given by the equation x = A + Bt + Ct2, where t represents time in seconds. What are the SI units of A, B, and C?

m, m/s, m/s2

A player kicks a soccer ball in a high arc toward the opponent's goal. At the highest point in its trajectory

neither the ball's velocity nor its acceleration are zero.

The slope of a position versus time graph gives

velocity.

A uniform 1200-N piece of medical apparatus that is 3.5 m long is suspended horizontally by two vertical wires at its ends. A small but dense 550-N weight is placed on the apparatus 2.0 m from one end, as shown in the figure. What are the tensions, A and B, in the two wires?

A = 910 N, B = 840 N

A 1-kg ball is released from a height of 6 m, and a 2-kg ball is released from a height of 3 m. Air resistance is negligible as they fall. Which of the following statements about these balls are correct? (There could be more than one correct choice.)

As they reach the ground, the 1-kg ball will be moving faster than the 2-kg ball. Both balls will reach the ground with the same kinetic energy.

Suppose that a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light. Which statement concerning its acceleration must be correct?

Its acceleration is positive.

A croquet mallet balances when suspended from its center of mass, as shown in the left part of the figure. If you cut the mallet into two pieces at its center of mass, as shown in the right part of the figure, how do the masses of the two pieces compare? (There could be more than one correct choice.)

The piece with the head of the mallet has the greater mass. It is impossible to tell.

A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the momentum change during the collision is correct? (There could be more than one correct choice.)

The small car and the truck experience the same magnitude momentum change.

An object is moving with constant non-zero velocity in the +x direction. The velocity versus time graph of this object is

a horizontal straight line.

Consider a flat steel plate with a hole through its center as shown in the figure. When the temperature of the plate is increased, the hole will

always expand with the plate.

In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is

completely inelastic.

If an operatic aria lasts for 5.75 min, its length expressed in seconds is x s, where x is

greater than 5.75.

If a flower is 6.5 cm wide, its width expressed in millimeters is x mm, where x is

greater than 6.5.

If the absolute temperature of an object is tripled, the thermal power radiated by this object (assuming that its emissivity and size are not affected by the temperature change) will

increase by a factor of 81.

An egg falls from a bird's nest in a tree and feels no effects due to the air. As it falls,

only its mechanical energy is conserved.

If A+B=C and their magnitudes are given by A + B = C, then the vectors A, B, and C are oriented

parallel to each other (in the same direction).

When you throw a pebble straight up with initial speed V, it reaches a maximum height H with no air resistance. At what speed should you throw it up vertically so it will go twice as high?

sqrt(2)V

The reason an astronaut in an earth satellite feels weightless is that

the astronaut is falling.

The absolute temperature of an ideal gas is directly proportional to which of the following quantities?

the average kinetic energy of its molecules

As one stretches a metal wire, which condition is reached first?

the proportional limit

Two metal spheres are made of the same material and have the same diameter, but one is solid and the other is hollow. If their temperature is increased by the same amount,

the two spheres remain of equal size.

The speed of a wave pulse on a string depends on the tension (F) in the string and the mass per unit length ( ) of the string. Tension has SI units of and the mass per unit length has SI units of What must be the combination of F and to determine the speed of the wave?

√(F/u)

Three small masses are positioned as follows: 2.0 kg at (0.0 m, 0.0 m), 2.0 kg at (2.0 m, 0.0 m), and 4.0 kg at (2.0 m, 1.0 m). Determine the coordinates of the center of mass (or center of gravity) of this system.

(1.5 m, 0.50 m)

Object 1 has three times the specific heat capacity and four times the mass of Object 2. The two objects are heated from the same initial temperature, T0, to the same final temperature Tf. During this process, if Object 1 absorbs heat Q, the amount of heat absorbed by Object 2 will be

(1/12)Q

The figure shows a graph of the velocity of an object as a function of time. What is the average acceleration of the object over the following time intervals? (a) From t = 0 s to t = 5.0 s (b) From t = 0 s to t = 8.0 s

(a) 2 m/s^2 (b) -2.5 m/s^2

A car with good tires on a dry road can decelerate (slow down) at a steady rate of about 5.0 m/s2 when braking. If a car is initially traveling at 55 mi/h(a) how much time does it take the car to stop?(b) what is its stopping distance?

(a) 4.9 seconds (b) 60 meters

A mechanic is examining the wheel of a bicycle to adjust the brake. With the bicycle off the ground, he manually rotates the wheel until it reaches an angular speed of 12.0 rad/s and then allows it to coast to a stop. If the wheel has a moment of inertia of 0.100 kg m2, and the wheel slows uniformly to a stop in 160 s, what is the magnitude of the retarding torque?

0.00750 N m

The radius of the earth is R. At what distance above the earth's surface will the acceleration of gravity be 4.9 m/s2?

0.41 R

How much work is required to stretch an ideal spring of spring constant (force constant) 40 N/m from x = 0.20 m to x = 0.25 m if the unstretched position is at x = 0.00 m?

0.45 J

A 0.12-kg block is held in place against the spring by a 35-N horizontal external force. The external force is removed, and the block is projected with a velocity when it separates from the spring, as shown in the figure. The block descends a ramp and has a velocity at the bottom of the ramp. The track is frictionless between points A and B. The block enters a rough section at B, extending to E. The coefficient of kinetic friction between the block and the rough surface is 0.26. The block moves on to D, where it stops. By how many centimeters was the spring initially compressed?

0.49 cm

An object is thrown upwards with a speed of 16 m/s. How long does it take it to reach a height of 7.0 m on the way up? Neglect air resistance.

0.52 s

The sum of two vectors of fixed magnitudes has the greatest magnitude when the angle between these two vectors is

0°

If Earth had twice its present mass but it orbited at the same distance from the sun as it does now, its orbital period would be

1 year.

At their closest approach, Venus and Earth are 4.20 × 1010 m apart. The mass of Venus is 4.87 × 1024 kg, the mass of Earth is 5.97 × 1024 kg, and G = 6.67 × 10-11 N m2/kg2. What is the magnitude of the gravitational force exerted by Venus on Earth at that point?

1.10 × 10^18 N

A 50-kg air conditioner is placed on top of a concrete pad that is 20 cm thick and has a cross-sectional area of 3.0 m2. What is the change in thickness of the pad caused by the air conditioner? Young's modulus for concrete is 2.3 × 1010 N/m2.

1.4 × 10^-9 m

0.0001776 can also be expressed as

1.776 × 10-4.

A ball is thrown with an initial velocity of 20 m/s at an angle of 60° above the horizontal. If we can neglect air resistance, what is the horizontal component of its instantaneous velocity at the exact top of its trajectory?

10 m/s

A wheel rotates through an angle of 13.8 rad as it slows down uniformly from 22.0 rad/s to 13.5 rad/s. What is the magnitude of the angular acceleration of the wheel?

10.9 rad/s2

A small but dense 2.0-kg stone is attached to one end of a very light rod that is 1.2 m long. The other end of the rod is attached to a frictionless pivot. The rod is raised until it is vertical, with the stone above the pivot. The rod is released and the stone moves in a vertical circle with no air resistance. What is the tension in the rod as the stone moves through the bottom of the circle?

100 N

A particularly scary roller coaster contains a loop-the-loop in which the car and rider are completely upside down. If the radius of the loop is with what minimum speed must the car traverse the loop so that the rider does not fall out while upside down at the top? Assume the rider is not strapped to the car.

11.4 m/s

A 900-kg car traveling east at 15.0 m/s suddenly collides with a 750-kg car traveling north at 20.0 m/s. The cars stick together after the collision. What is the speed of the wreckage just after the collision?

12.2 m/s

A bicycle has wheels that are 60 cm in diameter. What is the angular speed of these wheels when it is moving at 4.0 m/s?

13 rad/s

A pencil that is 15.7 cm long is released from a vertical position with the eraser end resting on a table. The eraser does not slip as it tips over. Treat the pencil like a uniform rod. What is the angular speed of the pencil just before it hits the table?

13.7 rad/s

In a museum exhibit of a simple pendulum, a very small but dense 6.0-kg ball swings from a very light 2.5-m wire. The ball is released from rest when the pendulum wire makes a 65° angle with the vertical, and it swings in a circular arc with no appreciable friction or air resistance. What is the tension in the wire just as the ball swings through its lowest position?

130 N

The thermal conductivity of aluminum is twice that of brass. Two rods (one aluminum and the other brass) of the same length and cross-sectional area are joined together end to end. The free end of the brass rod is maintained at 0°C and the free end of the aluminum rod is maintained at 200°C. If no heat escapes from the sides of the rods, what is the temperature at the place where the two rods are joined together?

133°C

The figure shows four vectors A, B, C, and D having magnitudes 10.0 m, 8.00 m, 6.00 m, and 2.00 m, respectively. Find the magnitude of the sum of these four vectors.

14.4 m

An object having a fixed emissivity of 0.725 radiates heat at a rate of 10 W when it is at an absolute temperature T. If its temperature is doubled to 2T, at what rate will it now radiate?

160 W

The volume coefficient of thermal expansion for gasoline is 950 × 10-6 K-1. By how many cubic centimeters does the volume of 1.00 L of gasoline change when the temperature rises from 30°C to 50°C?

19 cm^3

A 4.2-L flask of ideal neon gas (which is monatomic) is at a pressure of 3.3 atm and a temperature of 450 K. The atomic mass of neon is 20.2 g/mol. How many neon atoms are in the flask? (R = 8.31 J/mol K, 1 atm = 101 kPa, NA = 6.022 × 1023 molecules/mol)

2.3 × 10^23

Two identical objects are placed in a room with a temperature of 20°C. Object A has a temperature of 50°C, while object B has a temperature of 90°C. What is the ratio of the net power emitted by object B to the power emitted by object A?

2.8

An object with a mass of 10 kg is initially at rest at the top of a frictionless inclined plane that rises at 30° 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 shown. The coefficient of kinetic friction between the horizontal surface and the object is 0.20, and air resistance is negligible. Find the distance d.

20 m

A 5000-N force compresses a steel block by 0.0025 cm. How much force, applied over the same area, would be needed to compress the block by 0.0125 cm?

25,000 N

The figure shows a graph of the temperature of a pure substance as a function of time as heat is added to it at a constant rate in a closed container. If LF is the latent heat of fusion of this substance and LV is its latent heat of vaporization, what is the value of the ratio LV/LF?

3.5

A 50-kg load is suspended from a steel wire of diameter 1.0 mm and length 11.2 m. By what distance will the wire stretch? Young's modulus for steel is 2.0 × 1011 Pa.

3.5 cm

Two small objects, with masses m and M, are originally a distance r apart, and the gravitational force on each one has magnitude F. The second object has its mass changed to 2M, and the distance is changed to r/4. What is the magnitude of the new gravitational force?

32F

A car moving at a steady 10 m/s on a level highway encounters a bump that has a circular cross-section with a radius of 30 m. The car maintains its speed over the bump. What is the normal force exerted by the seat of the car on a 60.0-kg passenger when the car is at the top of the bump?

390 N

A chicken is running in a circular path with an angular speed of 1.52 rad/s. How long does it take the chicken to complete one revolution?

4.13 s

A projectile leaves the ground at 150 m/s and reaches a maximum height of 0.57 km. If there was no air resistance, at what angle above the horizontal did it leave the ground?

45 degrees

A car starts out when the air temperature is 288 K and the absolute (total) air pressure in the tires is 500 kPa. After driving a while, the temperature of the air in the tires increases to 298 K. What is the pressure in the tires at that point, assuming their volume does not change?

517 kPa

At what temperature is the rms speed of hydrogen molecules, H2, which have a molecular weight of 2.02 g/mole, equal to 2.0 km/s? The Boltzmann constant is 1.38 × 10-23 J/K and NA = 6.022 × 1023 molecules/mol.

51°C

A 1500-kg car traveling at 90 km/h toward the east suddenly collides with a 3000-kg car traveling at 60 km/h toward the south. The two cars stick together after the collision. What is the direction of motion of the cars after collision?

53.1° S of E

A Ferris wheel rotating at 20 rad/s slows down with a constant angular acceleration of magnitude 5.0 rad/s2. How many revolutions does it make while slowing down before coming to rest?

6.4

A ball is thrown straight up with a speed of 36 m/s. How long does it take to return to its starting point, assuming negligible air resistance?

7.3 s

It is necessary to determine the specific heat of an unknown object. The mass of the object is It is determined experimentally that it takes to raise the temperature What is the specific heat of the object?

7.46 J/kg K

An ice skater has a moment of inertia of 5.0 kg m2 when her arms are outstretched, and at this time she is spinning at 3.0 rev/s. If she pulls in her arms and decreases her moment of inertia to 2.0 kg m2, how fast will she be spinning?

7.5 rev/s

What is the sum of 1.53 + 2.786 + 3.3 written with the correct number of significant figures?

7.6

A block of mass m = 4.4 kg, moving on frictionless surface with a speed makes a sudden perfectly elastic collision with a second block of mass M, as shown in the figure. The second block is originally at rest. Just after the collision, the 4.4-kg block recoils with a speed of What is the mass M of the second block?

7.7 kg

An airplane undergoes the following displacements, all at the same altitude: First, it flies in a direction 30.0° east of north. Next, it flies due south. Finally, it flies 30.0° north of west. Use components to determine how far the airplane ends up from its starting point.

71.5 km