Question 1

Calculate the work done by a force, ,around a closed path,first going from P₁ (1,1)to P₂ (4,4)along path a and returning along path b.

Accepted Answer

A

Question 2

Susana ascends a mountain via a short,steep trail.Sean ascends the same mountain via a long,gentle trail.Which of the following statements is true?

Accepted Answer

Susana and Sean both ascend the same mountain, which means they reach the same height above the base level. Gravitational potential energy depends on the height gained and the mass of the object, not the path taken to reach that height. Since they reach the same height, they gain the same amount of gravitational potential energy, regardless of the steepness or length of their respective trails.

Question 3

The reference point for gravitational potential energy

Accepted Answer

The reference point for gravitational potential energy can be chosen arbitrarily. It is generally chosen based on convenience and ease of calculation. Some common choices for reference points include ground level, the lowest position ever reached by the object, and the initial position of the object. However, any position can be chosen as the reference point as long as it is consistent throughout the calculation.

Question 4

A 5200-kg cable car in Hong Kong is pulled a distance of 360 m up a hill inclined at 12º from the horizontal.The change in the potential energy of the car is

Accepted Answer

The change in potential energy is given by mgh, where h is the vertical height. h = 360 m * sin(12º). Calculate h and then use m = 5200 kg and g = 9.8 m/s² to find the change in potential energy.

Question 5

A 75-kg man climbs the stairs to the fifth floor of a building,a total height of 16 m.His potential energy has increased by

Accepted Answer

The answer of A 75-kg man climbs the stairs to...

Question 6

According to Quantum Chromodynamics,the force that keeps quarks confined within a proton (or neutron)increases as the separation between the individual quarks increases.Which statement below best represents this scenario?

Accepted Answer

According to Quantum Chromodynamics (QCD), the force that keeps quarks confined within a proton (or neutron) increases as the separation between the individual quarks increases. This is similar to stretching an elastic band, where the force required to pull the band increases as it stretches. Therefore, option B, "The quarks are tied together by elastic strings," best represents this scenario. Option A is incorrect as there is no evidence to suggest that the strings are non-stretchable. Option C is incorrect as quarks are bound together within a proton (or neutron), and do not move independently of each other. Option D is incorrect as the strong force, which binds quarks together, has a completely different functional form compared to the gravitational force. Option E is also incorrect as the potential energy of a quark actually increases with separation, due to the increased force required to keep them bound together.

Question 7

Which of the following statements is NOT correct?

Accepted Answer

Friction is NOT an example of a conservative force. Conservative forces are those for which the work done to move an object between two points is independent of the path taken, while frictional forces depend on the path taken.

Question 8

A body falls through the atmosphere (consider air resistance)gaining 20 J of kinetic energy.How much gravitational potential energy did it lose?

Accepted Answer

When a body falls through the atmosphere with air resistance, the gravitational potential energy lost is converted into kinetic energy and work done against air resistance. Since the body gains 20 J of kinetic energy, it must have lost more than 20 J of gravitational potential energy to also overcome the air resistance.

Question 9

The potential energy function for a conservative force acting in the x direction is shown in the figure on the right.Where would the particle experience a force directed to the right?

Accepted Answer

The answer of The potential energy function for a conservative...

Question 10

Which potential energy versus displacement curve best represents that of an extended spring?

Accepted Answer

The answer of Which potential energy versus displacement curve best...

Question 11

A projectile of mass m is propelled from ground level with kinetic energy of 450 J.At the exact top of its trajectory,its kinetic energy is 250 J.To what height above the starting point does the projectile rise?

Accepted Answer

The answer of A projectile of mass m is propelled...

Question 12

Calculate the work done by a force, ,along the path (0,0)$\to$P₁ (2,0)$\to$ P₂ (2,2).

Accepted Answer

The answer of Calculate the work done by a force,...

Question 13

The potential energy function for a conservative force acting in the x direction on a particle is shown below.The number of points where the net force on the particle is equal to zero are

Accepted Answer

The net force is equal to zero at points where the potential energy function has a minimum or maximum. From the given potential energy function, we can see that there are minima at points B, C, D, and E. Thus, the net force is equal to zero at these four points. The potential energy function also has a maximum at point A and a point of inflection at point F, but these do not correspond to points where the net force is equal to zero. Therefore, the best choice is C, which includes all the points where the net force is equal to zero.

Question 14

A woman runs up a flight of stairs.The gain in her gravitational potential energy is U.If she runs up the same stairs with twice the speed,what is her gain in potential energy?

Accepted Answer

The answer of A woman runs up a flight of...

Question 15

A block with a mass M = 4.85 kg is resting on a slide that has a curved surface.There is no friction.The speed of the block after it has slid along the slide sufficiently far for its vertical drop to be 19.6 m is

Accepted Answer

The speed of the block can be found using the conservation of energy principle, where the potential energy at the top is converted into kinetic energy at the bottom. The formula for this is $v = \sqrt{2gh}$, where $g = 9.8 \, \text{m/s}^2$ and $h = 19.6 \, \text{m}$. Plugging in these values gives $v = \sqrt{2 \times 9.8 \times 19.6} = 19.6 \, \text{m/s}$.

Question 16

The total mechanical energy of any system is

Accepted Answer

The total mechanical energy of a system is the sum of the kinetic energy and potential energy at any point. This means that as an object moves through space, its total mechanical energy remains constant as long as no external forces act on it. The kinetic energy is the energy of motion, while the potential energy is the energy associated with an object's position or configuration. By summing these energies together, we can calculate the total mechanical energy of the system.

Question 17

In magazine car tests an important indicator of performance is the zero to 60 mph (0 to 96.6 km/h)acceleration time.A time below 6 s is considered to be extremely quick.If a car with mass 1300 kg were dropped vertically from a great height,how long would it take to go from zero to 60 mph and what would the magnitude of the change in gravitational potential energy be during this time? (neglect air resistance)

Accepted Answer

The time to reach 60 mph under gravity is 2.74 s, and the change in gravitational potential energy is 468 kJ.

Question 18

Which of the following statements is true?

Accepted Answer

Kinetic energy, defined as $ \frac{1}{2}mv^2 $ (where $ m $ is mass and $ v $ is velocity), is always positive because mass and the square of velocity are always positive. Potential energy, however, can be negative depending on the reference point chosen. For example, in gravitational potential energy calculations, the potential energy can be negative if the reference point is chosen to be at a position higher than the object's position.

Question 19

A spring with force constant k = 300 N/m is compressed 9.0 cm.What is the potential energy in the spring?

Accepted Answer

The potential energy stored in a compressed spring is given by the formula $ \frac{1}{2}kx^2 $, where $ k $ is the spring constant and $ x $ is the compression distance. Here, $ k = 300 \, \text{N/m} $ and $ x = 9.0 \, \text{cm} = 0.09 \, \text{m} $. Plugging these values into the formula gives $ \frac{1}{2} \times 300 \times (0.09)^2 = 1.215 \, \text{J} $, which rounds to 1.2 J.

Question 20

Which of the following statements is true?

Accepted Answer

The answer of Which of the following statements is true?
...

Quiz 7: Conservation of Energy

Calculate the work done by a force, ,around a closed path,first going from P₁ (1,1) to P₂ (4,4) along path a and returning along path b.

Susana ascends a mountain via a short,steep trail.Sean ascends the same mountain via a long,gentle trail.Which of the following statements is true?

The reference point for gravitational potential energy

A 5200-kg cable car in Hong Kong is pulled a distance of 360 m up a hill inclined at 12º from the horizontal.The change in the potential energy of the car is

A 75-kg man climbs the stairs to the fifth floor of a building,a total height of 16 m.His potential energy has increased by

According to Quantum Chromodynamics,the force that keeps quarks confined within a proton (or neutron) increases as the separation between the individual quarks increases.Which statement below best represents this scenario?

Which of the following statements is NOT correct?

A body falls through the atmosphere (consider air resistance) gaining 20 J of kinetic energy.How much gravitational potential energy did it lose?

The potential energy function for a conservative force acting in the x direction is shown in the figure on the right.Where would the particle experience a force directed to the right?

Which potential energy versus displacement curve best represents that of an extended spring?

A projectile of mass m is propelled from ground level with kinetic energy of 450 J.At the exact top of its trajectory,its kinetic energy is 250 J.To what height above the starting point does the projectile rise?

The potential energy function for a conservative force acting in the x direction on a particle is shown below.The number of points where the net force on the particle is equal to zero are

A woman runs up a flight of stairs.The gain in her gravitational potential energy is U.If she runs up the same stairs with twice the speed,what is her gain in potential energy?

A block with a mass M = 4.85 kg is resting on a slide that has a curved surface.There is no friction.The speed of the block after it has slid along the slide sufficiently far for its vertical drop to be 19.6 m is

The total mechanical energy of any system is

Which of the following statements is true?

A spring with force constant k = 300 N/m is compressed 9.0 cm.What is the potential energy in the spring?

Which of the following statements is true?

Quiz 7: Conservation of Energy

Calculate the work done by a force, ,around a closed path,first going from P1 (1,1) to P2 (4,4) along path a and returning along path b.

Susana ascends a mountain via a short,steep trail.Sean ascends the same mountain via a long,gentle trail.Which of the following statements is true?

The reference point for gravitational potential energy

A 5200-kg cable car in Hong Kong is pulled a distance of 360 m up a hill inclined at 12º from the horizontal.The change in the potential energy of the car is

A 75-kg man climbs the stairs to the fifth floor of a building,a total height of 16 m.His potential energy has increased by

According to Quantum Chromodynamics,the force that keeps quarks confined within a proton (or neutron) increases as the separation between the individual quarks increases.Which statement below best represents this scenario?

Which of the following statements is NOT correct?

A body falls through the atmosphere (consider air resistance) gaining 20 J of kinetic energy.How much gravitational potential energy did it lose?

The potential energy function for a conservative force acting in the x direction is shown in the figure on the right.Where would the particle experience a force directed to the right?

Which potential energy versus displacement curve best represents that of an extended spring?

A projectile of mass m is propelled from ground level with kinetic energy of 450 J.At the exact top of its trajectory,its kinetic energy is 250 J.To what height above the starting point does the projectile rise?

Calculate the work done by a force, ,along the path (0,0) →\to→ P1 (2,0) →\to→ P2 (2,2) .

The potential energy function for a conservative force acting in the x direction on a particle is shown below.The number of points where the net force on the particle is equal to zero are

A woman runs up a flight of stairs.The gain in her gravitational potential energy is U.If she runs up the same stairs with twice the speed,what is her gain in potential energy?

A block with a mass M = 4.85 kg is resting on a slide that has a curved surface.There is no friction.The speed of the block after it has slid along the slide sufficiently far for its vertical drop to be 19.6 m is

The total mechanical energy of any system is

Which of the following statements is true?

A spring with force constant k = 300 N/m is compressed 9.0 cm.What is the potential energy in the spring?

Which of the following statements is true?

Calculate the work done by a force, ,around a closed path,first going from P₁ (1,1) to P₂ (4,4) along path a and returning along path b.