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jai6638
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A steel ball has a mass of 4 kg and rolls along a smooth level surface at 62 m/s.
a) Find its kinetic energy ( i found this.. )
b) At first, the ball was at rest on the surface. A constant force acted on it through a distance of 22 m to give it the speed of 62 m/s. What was the magnitude of the force?
so here's my thought process:
.5 mv^2 + mgh = .5mv^2 + mgh
0 = .5mv^2+mgh
-.5mv^2=mgh
mg=- .5mv^2/h
mg= - .5 x 4 x 62^2/22
mg= -350 N
is the above method correct?
Q2) In the 1950's, an experimental train that had a mass of 2.50x10^4 was powered across a level track by a jet engine that produced a thrust of 5x10^5 N for adistance of 509 m.
a) Find the work done on the train. ( found this to be 2.545E8)
b) Find the change in kinetic energy. ( 2.545E8)
c) Find the final kinetic energy of the train if it started from rest. ( how do i find this?? .5 mv^2 won't wrk since i don't know waht the velocity is )
d) find the final speed of the train if there were no friction ( how do i find this?? )
thanks much
a) Find its kinetic energy ( i found this.. )
b) At first, the ball was at rest on the surface. A constant force acted on it through a distance of 22 m to give it the speed of 62 m/s. What was the magnitude of the force?
so here's my thought process:
.5 mv^2 + mgh = .5mv^2 + mgh
0 = .5mv^2+mgh
-.5mv^2=mgh
mg=- .5mv^2/h
mg= - .5 x 4 x 62^2/22
mg= -350 N
is the above method correct?
Q2) In the 1950's, an experimental train that had a mass of 2.50x10^4 was powered across a level track by a jet engine that produced a thrust of 5x10^5 N for adistance of 509 m.
a) Find the work done on the train. ( found this to be 2.545E8)
b) Find the change in kinetic energy. ( 2.545E8)
c) Find the final kinetic energy of the train if it started from rest. ( how do i find this?? .5 mv^2 won't wrk since i don't know waht the velocity is )
d) find the final speed of the train if there were no friction ( how do i find this?? )
thanks much
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