A20 kg block slides to the left along a horizontal frictionless surface and hits an uncompressed spring of spring constant 810 n/m, which sends the mass back to the right with the same speed. for how long is the block in contact with the spring? a) 0.785 s b) 0.641 s c) 0.597 s d) 0.555 s e) 0.494 s

True or false: the revolution of the earth creates day and night as it rotates around the sun

What do elements in a family tend to share. a.) similar periods b.) similar groups c.) similar atomic symbols d.) similar chemical properties and characteristics

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.