Question
16 only
same at a later time as at an earlier time a) collisions between particles within the system. external forces acting on particles of the system. c) changes of momentum of individual particles within the system. internal forces acting between particles within the system. Q16. As a 1.0 kg object moves from point A to point B, it is acted by a single conservative f which does - 40 J of work on it during this motion. At point A the speed of the object is 10.0 m/s and the potential energy associated with the force is + 50 J. What is the potenti energy of the object at point B? a) +90 J b) +10 J c) +72 J d) +28 J e) +68 Q17. A 20.0 kg mass is fastened to a light spring (k = 380 N/m) that passes over a pulley as shown below. The pulley is frictionless, and the mass is released from rest when the spring unstretched. After the mass has dropped 0.4 m, what is its speed?
Explanation / Answer
Answer A
w=-delta U
-40=-delta U
+40=delta U
50 +40= 90J