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%

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30%

Friction exists only when two objects rub against each other. A. True B. False

If a net force of 5.0 N forward acts on a 0.60 kg toy car what is its acceleration

It's the year 2078, and you're traveling from Earth to the Moon. To determine how much fuel you need for the rocket ship, you measure your mass upon boarding. When you land on the Moon, your hasn't changed. Your , however, has changed.

Is the topic of atoms and elements a branch of physics?

1. When a star collapses to form a black hole, its mass a. decreases b. remains the same

The universe is believed to have been form from a very dense fireball billions of years ago.

What does the slope of the line on this velocity versus time graph represent? A. positive deceleration B. zero acceleration C. positive acceleration D. negative acceleration

Which of the following objects has the greatest kinetic energy? a baseball flying through the air at 90 miles per hour a baseball flying through the air at 45 miles per hour a baseball flying through the air at 20 miles per hour a baseball sitting

Peter found an amazing fact in an amusement park when he tried to ride the Magic Mountain Superman. Powerful magnets accelerate a car and its riders from zero to 45 m/s in 7 seconds. Suppose the mass of the car and riders is 5,600 kg.

The formula s = 16t2 gives the distance an object falls due to gravity, where s is the distance in feet and t is the time in seconds. how many feet will the object fall in 6 seconds?