Question

1. choose the best answer.

the sum of an objects kinetic and potential energy is its ____.
vector
thermal energy
static friction
gravitational force

1. choose the best answer using the picture of the measuring tool.

unlike copper, wood and plastic are poor ____ of electricity.
conductors
insulators
dischargers
developers

1. choose the best answer using the picture of the measuring tool.

there is no motion or change of direction when forces are ____.
balanced
unbalanced
unstable
stable

Explanation:

• Question 7: Kinetic energy is the energy of motion and potential energy is stored energy. The sum of these two is mechanical energy. However, looking at the options:
• A vector is a quantity with magnitude and direction (not related to energy sum).
• Thermal energy is related to heat (not the sum of kinetic and potential).
• Static friction is a force that opposes impending motion (not energy).
• Gravitational force is a force (not energy). But if we assume there was a typo/missing option (should be mechanical energy), but among given options, maybe it's a mis - phrased question. But if we consider basic energy concepts (even with option limitations), there is no correct option. But if we assume it's a trick question (maybe in a very basic context where they consider'mechanical' was mis - labeled), but strictly by the options, none is correct. But if we assume the question - maker intended'mechanical' (even if not an option), but since we have to choose from given:
• Question 8: Conductors allow electricity to flow easily (copper is a conductor). Insulators do not. Wood and plastic are insulators (but the question says "unlike copper (a conductor), wood and plastic are poor...". Since they are insulators, they are poor conductors.
• Question 9: When forces are balanced, the net force is zero. According to Newton's first law, an object at rest stays at rest (no motion) and an object in motion stays in motion (no change in direction) when the net force (balanced forces) is zero. Unbalanced forces cause acceleration (change in motion or direction). Unstable and stable are more about equilibrium states (not directly about motion change).

Answer:

1. None of the options (but if forced, no correct match).
2. A. conductors
3. A. balanced