If an object starts at rest and moves 90 meters south along a straight line for 3 seconds, what is its average velocity?

A. 90 m/s

B. 30 m/s, South

C. 30 m/s

D. 270 m/s, South

A vacuum cleaner has an energy input of 6.5 kWh and an energy output of 5.8 kWh. The efficiency of the vacuum cleaner, to the nearest percentage, is

How does increasing the speed of an object change its momentum?

The Calvin cycle can only happen in the dark. a. True b. False

Two students designed an experiment to study the effect of solar radiations on four cities of Earth. They used a globe to represent Earth and a light bulb to represent the sun.

Which equation is used to calculate the amount of electrical energy used? a) E = t : P b) E = t - P c) E = P + t d) E = P * t

A ball is being rolled by a normal push of 1000N. it is opposed by friction which has a force of 0.3kN and air resistance which has a force of 23N. Calculate the resultant force.

Consider a Young's two-slit experiment in which the wavelength of light is 37% smaller than the distance between the slits.

Which of the following situations would produce an average velocity of zero? A) a round-trip to school and back B) a horse galloping in a field C) the criss-crossing path of a flying bug D) a trip, first to the moon, then onto Mars

A 111.6 g sample of iron was heated from 0°C to 20°C. It absorbed 1004 J of energy. What is the specific heat capacity of iron?

A car is driving towards a brick wall at a constant velocity (don't try this at home!) and the driver honks the horn of the car. the sound of the horn reflects from the wall and the echo is heard by the driver.