CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

Choose the correct statement(s) from the following:
  1. A body can have energy and yet no momentum.
  2. The general form of Newton’s second law of motion is .
  3. A body having momentum must necessarily have kinetic energy.
  4. The relative velocity of two bodies in a head-on collision remains unchanged in magnitude and direction.


Solution

The correct option is C A body having momentum must necessarily have kinetic energy.
The general form of Newton’s second law is
Fext=dpdt=ddt(mv)=mdvdt+vdmdt
The form Fext=ma is valid only if dmdt=0, i.e. if mass does not change with time. Hence choice (a) is incorrect.    
Choice (b) is correct because a body at rest may have potential energy and yet no momentum. Choice (c) is also correct. A body has momentum if it has mass and velocity and a body having a mass and velocity must have kinetic energy. Choice (d) is incorrect because (as shown in Sec.9 in text) the relative velocity remains
unchanged in magnitude and gets reserved in direction; (v2 – v1) = - (u2 – u1). Hence the correct choices are (b) and (c).

flag
 Suggest corrections
thumbs-up
 
0 Upvotes



footer-image