Kinetic Energy Questions

The kinetic energies of two similar cars A and B are $100\text{J}$ and $225\text{J}$ respectively. On applying breaks, car A stops after $1000\text{m}$ and car B stops after $1500\text{m}$. If $F_A$ and $F_B$ are the forces applied by the breaks on cars A and B, respectively, then the ratio $F_A/F_B$ is:

A particle of mass $m$, charge $Q$, and kinetic energy $T$ enters a transverse uniform magnetic field of induction $\vec{B}$. After $3$ seconds, the kinetic energy of the particle will be:

A particle of mass $m$, charge $Q$ and kinetic energy $T$ enters a transverse uniform magnetic field of induction $\vec{B}$. After $3$ seconds the kinetic energy of the particle will be: