12. suppose a person uses a mechanical iack to lift half the weight of a car with a
mass of 1200 kg. during each stroke of the jack handle, the person's hand is
pushing for a distance of 40.0 cm but the car is lifted only 5.0 mm. a)
assuming the jack is 100% efficient. how much force must the person exen
on the handle as the car is lifted? (b) if the actual amount of force required on
the handle is 90.0 n, what is the actual efficiency of the jack?

b.transmitters send radio waves, and receivers capture radio waves.

gas and liquid

firearm identification is the process of analyzing the bullets and cartridge cases left at a crime scene to determine if they came from a particular firearm. marks on the bullets and cartridges may be common to every firearm of that type. these are called class characteristics.

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.