Abaseball is traveling (+30 m/s) and is hit by a bat. it leaves the bat traveling (-40 m/s). what is the change in the velocity? remember that direction is what makes velocity different than speed.

Explanation:

Change in velocity can be calculated by subtracting initial velocity from final velocity. The expression for the same is as follows.

where,     = change in velocity

                = final velocity

                = initial velocity

It is given that initial velocity is +30 m/s and final velocity is -40 m/s. Thus, calculate the change in velocity as follows.

                        = -40 m/s - (+30 m/s)

                        = (-40 - 30) m/s

                        = -70 m/s

Therefore, the change in the velocity -70 m/s.

305.7

explanation:

density =m/v

density =917/3.00

density = 305.

approximately = 305.7

in four significant figures

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.