Download App

PART - 1 CH - 5Work, Energy and Power — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysicsPART - 1 CH - 5Work, Energy and Power2 Marks
Question
Two identical blocks of mass 2 kg move towards each other with a uniform speed ( $2 m / s$ ) on a frictionless horizontal plane. They collide with each other and get attached to each other and comes to a state of rest. Calculate the work done by external forces and internal forces on the system of both the particles.
✓

Answer

Since there is no external force acting on the blocks.
$\therefore$ Work done by external forces $=0$
Kinetic energy before the collision of two block
$=\frac{1}{2} \times 2 \times(2)^2+\frac{1}{2} \times 2 \times(2)^2$
$=4+4=8 J$
On collision both blocks are attaches and comes to a state of rest. Hence their total energy will be zero.
$\therefore$ Work done by internal forces
$\begin{array}{l}
=k_{f}-k_{i} \\
=0-8=-8 J \quad Ans.
\end{array}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "2 Marks Questions" from PART - 1 CH - 5Work, Energy and Power→PART - 1 CH - 5Work, Energy and Power — all question types→Physics STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

Consider an ice cube of edge 1.0cm kept in a gravity free hall. Find the surface area of the water when the ice melts. Neglect the difference in densities of ice and water.
→
Prove that the motion of the particle system relative to the center of mass the total mass moment of the particle is zero.
→
Answer the following questions:A man with a wristwatch on his hand falls from the top of a tower. Does the watch give correcttime during the free fall?
→
A stone is dropped into a well and its splash is heard at the mouth of the well after an interval of 1.45 s . Find the depth of the well. Given that velocity of sound in air at room temperature is equal to $332 ms^{-1}$.
→
A cylinder rolls on a horizontal plane surface. If the speed of the centre is 25m/s, what is the speed of the highest point?
→
Two waves of wavelength 50 cm and 50.5 cm produce 6 pulse per second. Find the velocity of solution in gas
→
The charge on a proton is $+1.6 \times 10^{-19} \mathrm{C}$ and that on an electron is $-1.6 \times 10^{-19} \mathrm{C}$. Does it mean that the electron has a charge $3.2 \times 10^{-19} \mathrm{C}$ less than the charge of a proton?
→
A mass of 2kg is suspended with thread AB Thread CD of the same type is attached to the other end of 2kg mass. Lower thread is pulled gradually, harder and harder in the downward directon so as to apply force on AB. Which of the threads will break and why?
→
Two trains are travelling towards each other both at a speed of $90km/h$. If one of the trains sounds a whistle at $500Hz$, what will be the apparent frequency heard in the other train? Speed of sound in air = $350m/s$.
→
State Impulse-momentum theorem.
→