If a radioactive material has a half-life of 15 y what fraction of the material will remain after 30 y

A child of mass 25kg sits on a merry-go-round. The child is seated 4m from the centre of the merry-go-round and period of the motion is 27.3s. Calculate: a) the acceleration of the child b) the centripetal force

Which one of the following uses a lens and two mirrors?. a ... binoculars. c ... reflecting telescope. b ... microscope. d ... refracting telescope

Rachel and her family live in a region where Cacti, shirt grasses, and small bushes flourish. In which Boone do they live?

A 380-N girl walks down a flight of stairs son that she is 2.5 m below her starting level. What is the change in the girl's gravitational potential energy?

The mass of a stroller and the child it carries is 21.1 kg. A woman pushes the stroller with a force of 121 N at an angle of 41.0° to the vertical. The stroller experiences a friction force of 4.0 N. What is the stroller's acceleration forward?

The index of refraction of silicate flint glass for red light is 1.620 and for violet light is 1.660. A beam of white light in this glass strikes the glass-air interface at a 25.50∘ angle of incidence and refracts out into the air.

The locations of the major pressure and wind systems on the earth:

Which statements correctly describe the properties of heat? Select all that apply. Heat is an essential component of life on Earth. Heat is energy that flows from one object to another. Heat flows from a hotter object to a colder one.

A book is sitting on a table at rest. Which of the following best describes the forces acting on the book? A.

When NASA's Skylab reentered the Earth's atmosphere on July 11, 1979, it broke into a myriad of pieces. One of the largest fragments was a 1770-kg lead-lined film vault, and it landed with an estimated speed of 120 m/s.?