Answer:
The equation of equilibrium at the top of the vertical circle is:
\Sigma F = - N - m\cdot g = - m \cdot \frac{v^{2}}{R}
The speed experimented by the car is:
\frac{N}{m}+g=\frac{v^{2}}{R}
v = \sqrt{R\cdot (\frac{N}{m}+g) }
v = \sqrt{(5\,m)\cdot (\frac{6\,N}{0.8\,kg} +9.807\,\frac{kg}{m^{2}} )}
v\approx 9.302\,\frac{m}{s}
The equation of equilibrium at the bottom of the vertical circle is:
\Sigma F = N - m\cdot g = m \cdot \frac{v^{2}}{R}
The normal force on the car when it is at the bottom of the track is:
N=m\cdot (\frac{v^{2}}{R}+g )
N = (0.8\,kg)\cdot \left(\frac{(9.302\,\frac{m}{s} )^{2}}{5\,m}+ 9.807\,\frac{m}{s^{2}} \right)
N=21.690\,N
Net force
As it's negative the box will move left
Answer:
Part a)

Part b)

Part c)

Part d)
Net force on a closed loop in uniform magnetic field is always ZERO

Explanation:
As we know that force on a current carrying wire is given as

now we have
Part a)
current in side 166 cm and magnetic field is parallel
so we have

here we know that L and B is parallel to each other so

Part b)
For 68.1 cm length wire we have

here we know that


so we have


Part c)
For 151 cm length wire we have

here we know that


so we have


Part d)
Net force on a closed loop in uniform magnetic field is always ZERO

Answer:
momentum=mass×velocity
momentum =400kg×20m/s=8000kg.m/s