A car of mass $1000\; kg$ negotiates a banked curve of radius $90\;m$ on a frictionless road. If the banking angle is $45^{\circ}$, the speed of the car is

Question

( A ) $10 ms^{–1}$
( B ) $5 ms^{–1}$
( C ) $20 ms^{–1}$
( D ) $30 ms^{–1}$