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Science Library Quiz

Work, Energy and Power

Instructions: answer the questions, check them carefully, and when you are sure they are all right, press submit. The number of correct answers will be displayed.

Question 1: The mass of a planet is M and its radius is R. In order for a body of mass m to escape the gravitational attraction of the planet, its kinetic energy at the surface of the planet must be at least:




Question 2: On the ISS, the International Space Station, astronauts float around. This means that: ISS oranges




Question 3: A man pushes a car. After five seconds the car has gone from zero to 5 m/s. If the force the man pushes with is equal to his weight, how many times his mass is the car's mass?




Question 4: A ball bounces and rises to two-thirds its original height. After four bounces, how high will rise? Ball bouncing




Question 5: In Einstein's famous equation, $E = mc^2$, the energy E of a particle is equivalent to its mass m times the square of its velocity. In the case of his equation, he is dealing with particles travelling at the speed of light, c.
If the kinetic energy of a mass is $E = 1/2mv^2$, why is there not a $1/2$ in Einstein's equation?




Question 6: A mass is suspended by a string. The string is shortened gradually so the mass is raised h m. What is the net work done on the mass, and work done by the string?




Question 7: a weight is suspended from a string. A force F is applied horizontally to the weight and it rises h. What si the net work done by the string and F?




Question 8: A ball on a horizontal frictionless surface is travelling at speed v. It encounters a speed bump which has a rise of height h, before returning to the original horizontal plane. What is the minimum speed of the ball so that the ball can pass the barrier?




Question 9: Which of these energy conversions is the most efficient at doing useful work?




Question 10: What is conserved in an inelastic collision in a closed system?




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