An office worker smacks a table, bringing his hand to rest in 0.0025 seconds from an initial speed of 4.00 m/s. How much force is exerted on the table, taking the effective mass of his forearm and hand to be 1.5 kg? (Answer in 1 decimal place, in kilo-newtons, no unit) UNIT: kN Add your answer

A stationary 1.57-kg potato is struck by a stick, delivering a horizontal force of F(t) = at — bt² where t is the time in milliseconds from the instant the stick first contacts the potato. Find the potato's speed as it loses contact with the stick at t = 3.56 ms if a = 1,222 N/(ms) and b = 22 N/(ms)². (Hint: Be very careful with units.) V = m/s

lower a crate of mass ?1=5.00 kgm1=5.00 kg to the bottom of a steep ravine of height ?=25.0 mH=25.0 m. The crewman of mass ?2=55.6 kgm2=55.6 kg is walking while holding the rope, being careful to lower the crate at a constant speed of ?0=1.50 m/sv0=1.50 m/s. Unfortunately, when the crate reaches a point ℎ=13.9 mh=13.9 m above the ground, the crewman steps on a slick patch of ice and slips. The crate immediately accelerates toward the ground, dragging the hapless crewman across the ice and toward the edge of the cliff. Assuming the ice is perfectly slick, so that there is no friction between the crewman and the ice once he slips and falls down, at what speed ?1v1 will the crate hit the ground? Assume also that the rope is long enough to allow the crate to hit the ground before the crewman slides over the side of the cliff, and that the pulley is frictionless. ?1

A car of mass 1670kg initially at a speed of 80 km/m crushes into a wall, if the accident lasted for 0.2 sec. what is the amount of force exerted in the car during the crash