Physics
posted by Sandhya .
Force F causes displacement d of a 20Kg object starting from rest along a frictionless path. F= 10 N i + 50 N j + 15 N k and d= 10 m i + 60 m k
A) Calculate the work done by the force.
B) Calculate the angle between the vectors F and d.
C) Calculate the final speed of the object.

A) The work done is the scalar product of the F and d vectors.
B) The cosine of the angle between the two vectors is the ratio of the scalar product (obtained in part (A)) to the product of the magnitudes os the F and d vectors.
C) I do not understand why the displacement is not in the direction of the force, since it starts out motionless and there is no friction