Agirl on the swing throws a ball at the velocity of positive +7.5 m/s relative to the swing. when the ball leaves her hand, the girl has a velocity of +13.5 m/s relative to the ground. what is the velocity of the ball relative to the ground when she throws it?

a. +2 m/s
b.+6 m/s
c.+21 m/s
d. +101.25 m/s

**urgent** roberto plans to use two transformers to reduce a voltage of 120 v to 4 v. he uses a transformer that has 300 coils in the primary winding and 50 coils in the secondary winding. he has four other transformers, as listed in the table. which transformer should roberto use to have an ending voltage of 4 v? a- w b-xc- yd- z

How can you increase the strength of an electromagnet?

What was the first instrument to ever record an earthquake?