Answer:
a) T; b) F; c) F; d) T; e) T; f) T
Explanation:
a) True, since the equation of work done on a spring is
b) False, it will be only mgh.
c) False, since it is , no direction involved.
d) True, since the measured speed of objects depends from the reference frame of the observer.
e) True, since its formula is and both terms are positive.
f) True, since the centripetal force the Earth feels, which is the gravitational atraction the Sun exerts, is perpendicular to its circular trajectory.