Jan and Len throw identical rocks off a tall building at the same time. The groundnear the building is flat. Jan throws her rock straight downward. Len throws his rockdownward and outward such that the angle between the initial velocity of the rock andthe horizon is 30◦. Len throws the rock with a speed twice that of Jan’s rock. If airresistance is negligible, which rock hits the ground first?

Both the rocks land together.

Explanation:

Given:

initial speed of Jan,

initial speed of Len,

direction of velocity by Jan with respect to vertical down direction,

direction of velocity by Len with respect to vertical down direction,

Now velocity of the rock by Len in the vertically downward direction:

Form the equation of motion:

where:

height covered by the object

initial velocity of the object

acceleration due to gravity

time taken by the object to fall the height

Since the velocity of both the rocks is same in the vertical direction are thrown form the same height therefore both of the rocks will land together.

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation:

object 2 because all the other ones are wrong