Q2 A baby drops a. 25 kg block out of a high rise window Q2 A baby drops a .25 kg block out of a high rise window. What is the force on Earth due to the block, and what is Earth’s resulting acceleration? The mass of Earth is 6.0 x 10 24 kg. mblock = 0.25 kg earth = 6.0 x 10 24 kg g = 9.8 m/s2 F earth on block = ? aearth = ? F earth on block = mblock a = .25 kg (-9.8 m/s2) F earth on block = -2.54 kg*m/s2 = -2.54 N

F earth on block = -2.54 N (from 1st problem solved) Use Newton’s third Law to find F block on earth mblock = 0.25 kg m earth = 6.0 x 10 24 kg F earth on block = -2.54 N (from 1st problem solved) F block on earth = -F earth on block F block on earth = -(-2.54N) F block on earth = 2.54 N F earth on ball =

Substitute: Fnet = m earth a earth 2.54 N = 6.0 x 10 24 kg * a earth Use Newton’s Second law to find the aearth because of the net force caused by the block hitting it. Fnet = 2.54 N m earth = 6.0 x 10 24 kg Substitute: Fnet = m earth a earth 2.54 N = 6.0 x 10 24 kg * a earth 6.0 x 10 24 kg 6.0 x 10 24 kg 4.2 X 10 -25 N/kg = a earth 3 X 10 -25 m/s 2 = a earth kg * m/s2 kg