What is a half-life the reactive half of a radioactive substance the amount of time it takes for all of a radioactive substance to decay the amount of time it takes for half of a radioactive substancec to decay half the time it takes for a radioactive substance to break down

Aprojectile is launched horizontally 10m above the ground and with an initial velocity of 15 m/s. a) sketch the trajectory using an appropriate coordination system. b) how long for the projectile to reach the ground. c) how far did projectile travel horizontally before striking the ground. d) determine the projectilex & y position at t-1.3s e) determine the magnitude and direction of projectile velocity at t= 1.3s f) determine the magnitude and direction of projectile acceleration at t-1.3s

An object moves from position +34m to the position -15m in 15 seconds. what is the total displacement? what is the total velocity?

Abookcase has a mass of 38 kg and the coefficient of friction between it and the floor is 0.82 what is the maximum force of friction between the bookcase and the floor a 372n b 305n c 412n d 449n