If an arrow with the mass of 30 grams, sits in a bow with the potential energy of 70 J, what would the velocity of the arrow be after it left the bow. Assume no energy loss. 2.2 m/s
68 m/s
4.7 m/s
4700 m/s

68m/s

Explanation:

Given parameters:

Mass = 30g  = 0.03kg

Potential energy  = 70J

Unknown:

Velocity  = ?

Solution;

Since there is no loss in energy, the potential energy and kinetic energy will be the same when shot;

              P.E = K.E

            K.E  =  P.E  = m v²

                        70 =  x 0.03 x v²  

                         70 = 0.015v²

                           v = 68m/s

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:

when a device is used in a circuit in which the voltage is 81 v, the current flowing through the device is 3 a. what is the resistance of the device?

a. 27 ω

b. 40.5 a

c. 243 ω

d. 243 a

the correct answer is a. 27