A Carnot engine takes 3000 J from a reservoir at 600 K, does some work, and discards some heat to a reservoir at 300 K. What is its efficiency?

50%

60%

20%

30%

As long as the net force on a falling object is not zero, the object will ... (will give brainliest!)

Which of the following is not a way in which energy use can be reduced? insulating appliances setting the thermostat two degrees lower in the winter adding weather stripping to windows and doors replacing fluorescent bulbs with incandescent lighting

Light rays bend as they pass from air into water at an angle (not 90 degrees). This is refraction. Which quantity doesn't change when light refracts? 1. average speed of light 2. wavelength of light 3. index of refraction of the material 4.

Definition of artficial and natural radioactivity

A spring gun is used to project a 0.5 kg ball, in order to perform this experiment the spring was initially compressed by 0.005 m. Find the ball's speed when it leaves the gun, if the spring constant is 395 N/m.

Crystallization is a separation technique used to produce rock candy from a sugar solution. true or false

A car traveling in a straight line has a velocity of 3.79 m/s at some instant. After 5.4 s, its velocity is 11.9 m/s. What is its average acceleration in this time interval? Answer in units of m/s 2

The periodic law states that elements that have similar properties appear ... a. to the left of each other b. to the right of each other c. at every 10th element d. at regular intervals

An expert archer tried to shoot an arrow into a target lying at the bottom of a shallow pool. Even though the water did not change the direction of the arrow, the archer missed the mark by several inches.

Which of the following best describes a mechanical wave? A. A periodic disturbance of a medium. B. A movement of matter. c. A transfer of energy. D. When energy is converted from one form to another.