Answer:
3 and 2
May be
ok may be subscribeIsenberg Isenberg Ignatius
v = speed of the source of sound or the train towards the listener or switchman = 40 m/s
V = actual speed of sound = 340 m/s
f = actual frequency of sound as emitted from source or the train = 1000 Hz
f' = frequency as observed by the listener or by switchman = ?
Using Doppler's law , frequency observed by a listener from a source moving towards it is given as
f' = V f /(V - v)
inserting the values
f' = 340 x 1000 /(340 - 40)
f' = 340 x 1000/300
6 J is the impulse caused by the change in velocity of 2 kg box from 2 m/s to 5 m/s.
Answer:
The magnitude of impulse is 6 J.
Explanation:
Impulse is the force acting on any object for a given time interval. As force is equal to the product of mass and acceleration and acceleration is the rate of change of velocity with time. Then the product of force with time interval will be equal to the product of mass with change in velocity.
F = m a = 
FΔt = mΔv
Impulse = FΔt=mΔv
As the mass of box is given as 2 kg and the velocity changes from 2 m/s to 5 m/s, then the impulse = 2 × (5-2) = 2 ×3 =6 J
So 6 J is the impulse caused by the change in velocity of 2 kg box from 2 m/s to 5 m/s.
Answer: Technician B is right.
Explanation:
Evacuation process is used in refrigeration systems to remove moisture, air and non-profit condensable gases in order to achieve maximum function of the system.
vacuum pump is used to draw the sealed AC system into a vacuum. Evacuation of a refrigerant system also helps to maintain pressure, this is so as pulling a vacuum on the system is simply removing matter (mostly air and nitrogen) from inside the system so that the pressure inside drops below atmospheric pressure.
