If the frequency of incident light falling on a metallic surface is doubled, maximum kinetic energy of…
If the frequency of incident light falling on a metallic surface is doubled, maximum kinetic energy of emitted photoelectrons
increases to slightly more than double.
remains the same.
becomes twice.
decreases to slightly more than double.
Solution
For a bullet of mass $m=20 \mathrm{~g}=0.02 \mathrm{~kg}$ moving with a velocity $v=200 \mathrm{~m} / \mathrm{s}$ :
1. Impulse $J$ :
$J=m \times v=0.02 \times 200=4 \mathrm{Ns}$
2. Average force $F_{\text {avg }}$ (assuming time $t=\frac{1}{50} \mathrm{~s}$ ):
$F_{\mathrm{avg}}=\frac{J}{t}=\frac{4}{\frac{1}{50}}=200 \mathrm{~N}$
Thus, Answer (4): $4 \mathrm{Ns}, 200 \mathrm{~N}$ is correct.