Acceleration=force/mass=28/(10+4)=2m/s^2
force10kg=ma=10*2
force4kg=ma=(10*2)=20
the4 kg is pushing against the 10kg block
vf=vi+at
-10=20*28/14 * t
t=30/2=15sec
i hope this can help you.
The kinetic energy decreases
Answer:
The magnitude of the resultant of the magnetic field is 
Explanation:
Given that,
Current = 40 A
Magnetic field 
Distance = 22 cm
We need to calculate the magnetic field
Using formula of magnetic field

Where, r = distance
I = current
Put the value into the formula


We need to calculate the magnitude of the resultant of the magnetic field
Using formula of resultant

Put the value into the formula


Hence, The magnitude of the resultant of the magnetic field is 
<span>The rate of change in velocity is acceleration.</span>