A railroad car with a mass of 20,000 kg rolls into a second stationary car with a mass of 40,000 kg. The cars latch together and move off with a speed of 1.2 m/s. How fast was the first car moving before the collision?


3.6 m/s

Physics & Space Science

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You are alone in space and your tether brakes and you are floating motionless relative to your spaceship, which is located a frustrating 10 meters away. Your spacesuit has no jet pack and you have no air to spare. All you have is your wrench. How can you return to your ship?

Fill in the blank(s) with the appropriate word(s).

Physics & Space Science

An office building is constructed with a 6 inch space between the floor and the ceiling of the next lower floor, as shown. If air passes through the space at 65ºF determine the convective heat transfer per unit area when the floor and ceiling are 75ºF.

Physics & Space Science

Spectral Series: What is the shortest wavelength in the Balmer series?

A. 328 nm B. 365 nm C. 456 nm D. 656 nm E. 820 nm

Physics & Space Science

A bicycle that travels four as fast as another when braking to a stop will skid

A) twice as far. B) four times as far. C) eight times as far D) sixteen times as far. E) depends on the mass of the bike

Physics & Space Science