Question

Two workers push a crate to the right with a force of 325 lbs. The motion is opposed by a static frictional force of 300 lbs. Find the net force.

A 25lbs
B 25lbs to the right
C 16lbs
D 16lbs to the right

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A 17,500 kg railroad car traveling 8.00 m/s to the east collides and couples with a stopped 22,500 kg railroad car. What is the velocity of the joined railroad cars after the collision?

A 3.50 m/s west
B 7.00 m/s west
C 3.50 m/s east
D 7.00 m/s east

Answer 1

bady To dletermine free the net WWe se the force diagra m In this diaqram the crate is represented its motion is along dot, 4 aus a 325265 FR the 300bt l-axi5. The diagram makes it clear that att along added as the forces a direction, there fore thery one be can colinear vectorr to oblain the net Force The net Force workers push a crate in the ignt F, - here direction 325 Lbs f staric Frichonal Force 300 ebs The net Force 2825-300) b 25 65 is positive, et will move to right side as it Option to the ght is Orreot answer pesfectly indastic collision This s q There fore conseruation of momantum. We can w5e Basically, the tmomentum be fore must be the same tmomentum the empaet after as the P m momentu m case our m2 mit ma Ve ? m2 22,500 kg, 42

19,500) x 8 +22,500)x0 17500t 22, 500) V -1 40,000 V 140,000 40000 403000 .5 ms V = oF joined raulroad cars to wards eaust after the Yel o city Collision is .5 m15 plus sign that, joined railroad as it indicate Since direetion an the same accalerate oill Cars collision before tmoves is correct angwer -ophion