A wooden block, initially at rest on the ground, is pushed by a force which increases linearly with time $t$. Which of the following curve best describes acceleration of the block with time:

• A

  
  
• B

  
  
• C

  
  
• Correct answer
  D

  
  

Solution

$\mathrm{F}=\mathrm{ma} \Rightarrow \mathrm{a}=\frac{\mathrm{F}}{\mathrm{m}}=\frac{\mathrm{kt}}{\mathrm{m}}$ a vs $t$ will be straight line passing through origin.

Hence, the correct answer is option: 'D'.