1. a 5 -newton force cause a spring to strech 0.2m. what is the potential energy stored in the stretch spring?
2.a student does 60 J of work pushing a 3kg box up the full length of a ramp that is 5m long. what is the magnitude of the force applied to the box to do this work?
3.during a s interval, the velocity of an object changes from 25m/s east to 15m/s east.determine the magnitude and direction of the acceleration of the object.
explain in details
physics problems (3)
2007-04-29 1:50 pm
回答 (1)
2007-04-29 8:31 pm
✔ 最佳答案
1.F = 5 N, Δx = 0.2 m
Potential energy stored in the stretched spring P.E.
= F•Δx
= 5 x 0.2
= 1 J
==========
2.
W = 60 J, s = 5 m
W = F•s
Force applied to the box F
= W / s
= 60 / 5
= 12 N
==========
3.
Direction to the east = +ve
Direction to the west = -ve
u = +25 m/s, v = +15 m/s, t = 1 s
v = u + at
Acceleration a
= (v - u) / t
= (15 - 25) / 1
= -10 m/s2
Magnitude of acceleration = 10 m/s2
Direction of acceleration : pointing to the west
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