Home
Class 12
PHYSICS
As shown in (Fig. 3.131), a dust particl...

As shown in (Fig. 3.131), a dust particle with mass `m = 5.0 xx 10^-9 kg` and charge `q_0 = 2.0 n C` starts from rest at point a and moves in a straight line to point `b` What is its speed `v` at point `b` ?
.

A

` 2. 65 cms^ ( - 1 ) `

B

`3.65 cms^( - 1 ) `

C

` 4.65 cms ^( -1 ) `

D

`5.65 cms^ ( -1 ) `

Text Solution

Verified by Experts

The correct Answer is:
C

According to conservation of energy, we get `K_(a)+U_(a)=K_(b)+U_(b)`
Here, `K_(a)=0` and the potential energies are `U_(a)=q'V_(a) and U_(b)=q'V_(b)`
`therefore 0+q'V_(a)=(1)/(2)mv^(2)+q'V_(b)`
`or v=sqrt((2q'(V_(a)-V_(b)))/( m))` `or v=sqrt((2q'(V_(a)-V_(b)))/( m))`
`V_(a)=(9.0xx10^Nm^(2)C^(-2)) ((3xx10^(-9)C)/(0.01m)+(-3xx10^(-9)C)/(0.02m))=1350V`
`F_(b)=(9.0xx10^(9)Nm^(2)C^(-2)) ((3xx10^(-9)C)/(0.02m)+(-3xx10^(-9)C)/(0.01m))=-1350V`
`therefore v=sqrt((2(2xx10^(-9)C)(2700V))/(5xx10^(-3)kg))=4.65xx10^(-2)ms^(-1)`
Promotional Banner

Similar Questions

Explore conceptually related problems

As shown in figure a dust particle with mass m = 5.0 × 10–9 kg and charge q0 = 2.0 nC starts from rest at point a and moves in a straight line to point b . What is its speed v at point b?

A particle starts from rest at t=0 and moves in a straight line with an acceleration as shown below. The velocity of the particle at t=3 s is

A particle starts from rest at time t=0 and moves on a straight line with acceleration as plotted in fig. The speed of the particle will be maximum after time.

A particle starts motion from rest and moves along a straight line. Its velocity-time graph is shown. Find out speed of particle at t=2s and at t=3s .

A particle starts motion from rest and moves along a straight line. Its acceleration-time graph is shown. Find out speed of particle at t=2s and at t=3s.

The fig. shows the v-t graph of a particle moving in straight line. Find the time when particle returns to the starting point.

A particie of mass 10 kg is driven by a machine that delivers a constant power of 20 watts. If particle starts from rest and moves along a straight line, then force (in Newton) on particle at time t(t> 0) is

Three point particles of masses 1.0 kg, 1.5 kg and 2.5 kg are placed at three corners of a right angle triangle as shown in figure. The centre of mass of the system is at a point :

Three point particles of masses 1.0 kg, 1.5 kg and 2.5 kg are placed at three corners of a right angle triangle as shown in figure. The centre of mass of the system is at a point :

If a particle moves from the point A(1 , 2 , 3) to the point B( 4 , 6 ,9) , its displacement vector be