Abackpack has a mass of 8 kg. it is lifted and given 54.9 j of gravitational potential energy. how high is it lifted? acceleration due to gravity is g = 9.8 m/s2.

The potential energy for a lifted object is U = m*a*h

where m is the mass, h is the height and a is the acceleration.

in our problem the mass is m = 8kg, the height is the thing we want to find, a is the gravitational acceleration, 9.8 m/s^2 and U = 54.9j

then our problem is:

54.9j = h*9.8*8 kg*m/s^2

then h = 54.9/(9.8*8) = 0.7m

Then the backpack is lifted 0.7 meters.

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: