Step 1: Displacement equationsThe proton and the alpha particle both start from rest, so their displacement after some time is given by:s=21​at2.Since they travel the same distance:21​aα​tα2​=21​ap​tp2​This means:aα​tα2​=ap​tp2​Step 2: Acceleration in an electric fieldThe acceleration of a charged particle in an electric field E is:a=mqE​- For a proton, charge =e, mass =mp​- For an alpha particle, charge =2e, mass =4mp​So: −ap​=mp​eE​−aα​=4mp​2eE​=2mp​eE​Step 3: Substitute accelerations into equationPlug the accelerations into the earlier equation:(2mp​eE​)tα2​=(mp​eE​)tp2​Step 4: Solve for time ratioDivide both sides by mp​eE​ :2tα2​​=tp2​This gives: tα2​=2tp2​Taking square roots:tα​=2​tp​So,tα​tp​​=2​1​ortp​:tα​=1:2​