1. Assume that the dunes in a field of barchans sand dunes are moving at an average long-term rate of 30 meters (about 100 feet) a year. How many years does it take a dune to move a distance of 500 meters?

AHA recommends for children age 2 and older should participate in a minimum of 30 minutes of moderate-intensity physical activity each day 45 minutes of moderate-intensity physical activity each day 75 minutes of moderate-intensity physical activity

Which of the following describes effort force?

A thermometer is placed in water in order to measure the water's temperature. What would cause the liquid in the thermometer to rise? A. The molecules in the water move closer together. B. The molecules in the thermometer's liquid spread apart. C.

A horizontal jet of water is made to hit a vertical wall with a negligible rebound. If the speed of water from the jet is 'v', the diameter of the jet is 'd' and the density of water is 'p', then what is the force exerted on the wall by the jet of

A crow who wants to eat a snail will drop it from a high place to crack the snail's shell and expose the tasty flesh. In order to crack the snail's shell, it must be going 15 m/s when it hits the ground. Assume that the snail free falls.

If an astronaut moved away from the earth towards the moon, how would the gravitational forces between the earth and the astronaut change? How would the gravitational forces between the moon and the astronaut change?

A race car starts from rest and speed up uniformly to the right until it reaches a maximum velocity of 60m/s in 15 sec

The magnitude of a velocity vector is called speed. suppose that a wind is blowing from the direction n45°w at a speed of 40 km/h. (this means that the direction from which the wind blows is 45° west of the northerly direction.

The y component of the electric field of an electromagnetic wave traveling in the + x direction through vacuum obeys the equation Ey = (375 N/C) cos[kx - (2.20 * 1014 rad/s) t]. What is the wavelength of this electromagnetic wave? (c = 3.

The work of Subrahmanyan Chandrasekhar is likely to have been most influenced by the work of which of the following scientists? A. Albert Einstein B. Edwin Hubble C. Marie Sklodowska-Curie D. Lord Kelvin