Select the statement(s) that accurately describes the diagram.Neglect the effect of frictional forces.

Question

A) Mechanical energy at position A is equal to mechanical energy at position D
B) If K1 = 3.0 J at position C, then K2 = 3.0 J at position E
C) If K1 = 3.0 J at position C, then U2 = 3.0 J at position E
D) U1 at position C is less than U2 at position
E) Kinetic energy is zero at position A and B

The pendulum has the ball swinging, A is to the left, and E is to the right.

Answer 1

To analyze the statements regarding the diagram of the pendulum, we can apply the principles of conservation of mechanical energy. Mechanical energy, which is the sum of kinetic energy (K) and potential energy (U), remains constant in the absence of frictional forces.

Let’s evaluate the statements one by one:

A) Mechanical energy at position A is equal to mechanical energy at position D.

• True. Since there is no friction, mechanical energy is conserved throughout the pendulum's swing. Therefore, the total mechanical energy at position A and position D will be the same.

B) If K1 = 3.0 J at position C, then K2 = 3.0 J at position E.

• False. Position E is likely at a higher point than position C if it’s at the other side of the swing, which means that the potential energy will be greater and thus the kinetic energy will be less than 3.0 J at position E.

C) If K1 = 3.0 J at position C, then U2 = 3.0 J at position E.

• False. While the total mechanical energy would be constant, K1 does not equal U2 at position E unless the total mechanical energy is specifically 6.0 J (in which case U2 would be 3.0 J). Without that information, this statement cannot be assumed true.

D) U1 at position C is less than U2 at position E.

• True. Typically, position C (lower point) will have lower potential energy compared to position E (higher point). Thus, U1 < U2.

E) Kinetic energy is zero at position A and B.

• True for position A but false for position B. At position A (the highest point), the kinetic energy is indeed zero as the pendulum stops momentarily before reversing direction. However, at position B, which is in the middle of the swing, the pendulum would possess kinetic energy as it is moving.

In summary, the true statements are:

• A) True
• D) True
• E) True (only at A, not at B)

So, we conclude:

• A and D are accurate. E is only partially accurate with respect to A.

Answer 2

Please fill in this paragraph accurately.

The law of conservation of energy states energy cannot be created or destroyed, but it can be converted from one form into another. On a frictionless surface, all the potential energy an object possesses is converted into ? energy. Therefore, the ? energy of an object is equal to the total energy of the system. However, if non-conservative forces are present, such as friction, then kinetic energy is ? and thermal energy is produced.

Please choose from the following words:
kinetic

mechanical

transformed

destroyed

friction

thermal

Answer 3

Here is the completed paragraph with the appropriate words filled in:

The law of conservation of energy states energy cannot be created or destroyed, but it can be converted from one form into another. On a frictionless surface, all the potential energy an object possesses is converted into kinetic energy. Therefore, the mechanical energy of an object is equal to the total energy of the system. However, if non-conservative forces are present, such as friction, then kinetic energy is destroyed and thermal energy is produced.