When landing after a spectacular somersault, a 40.0 kg gymnast decelerates by pushing straight down on the mat. calculate the force she must exert if her deceleration is 7 times the acceleration of gravity?

Plss anybody know how to do this? ? i need the answers from a through d

John throws .4 kg ball with velocity of 18 m/s. hits .2 kg bottle and bottle flies 25 m/s. how fast is ball traveling after hitting the bottle?

9.98 kg of r-134a at 300 kpa fills a rigid container whose volume is 14 l. determine the temperature and total enthalpy in the container. the container is now heated until the pressure is 600 kpa. determine the temperature and total enthalpy when the heating is completed. use data from the steam tables.