Home
Class 12
PHYSICS
A car moves from X to Y with a uniform s...

A car moves from `X` to `Y` with a uniform speed `v_u` and returns to `X` with a uniform speed `v_d`. The average speed for this round trip is :
(a) `(2v_(d)v_(u))/(v_(d)+v_(u))` (b) `sqrt(v_(u)u_(d))` (c) `(v_(d)v_(u))/(v_(d)+v_(u))` (d) `(v_(u)+v_(d))/(2)`

A

`(v_(u)+v_(d))/(2)`

B

`(2v_(d)v_(u))/(v_(d)+v_(u))`

C

`sqrt(v_(u)v_(d))`

D

`(v_(d)v_(u))/(v_(d)+v_(u))`

Text Solution

Verified by Experts

The correct Answer is:
B
Average speed `=("Total distance")/("Total time")`
`=(2d)/((d)/(v_(u))+(d)/(v_(d)))=(2v_(d)v_(u))/(v_(d)+v_(u))`
Promotional Banner

Similar Questions

Explore conceptually related problems

In the figure the pulley P moves to the right with a constant speed u . The downward speed of A is v_(A) and the speed of B to the right V_(B) .

The function u=e^x sin x ; v=e^x cos x satisfy the equation a. v(d u)/(dx)-u(d v)/(dx)=u^2+v^2 b. (d^2u)/(dx^2)=2v c. (d^2v)/(dx^2)=-2u d. (d u)/(dx)+(d v)/(dx)=2v

Ultrasonic, Infrasonic and Audible waves travel through a medium with speeds v_(u), v_(l), v_(a) respectively, then

Let u(x) and v(x) are differentiable function such that (u(x))/(v(x))=6 . If (u'(x))/(v'(x))=p and ((u(x))/(v(x)))'=q then value of (p+q)/(p-q) is equal to

Find each of the products: (4/3u^2v w)xx\ (-5u v w^2)xx(1/3v^2w u)

If u=sin(mcos^(-1)x),v=cos(msin^(-1)x),p rov et h a t(d u)/(d v)=sqrt((1-u^2)/(1-v^2))

If u=sin(mcos^(-1)x),v=cos(msin^(-1)x),p rov et h a t(d u)/(d v)=sqrt((1-u^2)/(1-v^2))

Two particles are projected from a point at the same instant with velocities whose horizontal and vertical components are u_(1), v_(1) and u_(2), v_(2) respectively. Prove that the interval between their passing through the other common point of their path is (2(v_(1)u_(2) - v_(2) u_(1)))/(g (u_(1) + u_(2))

If a ,b,c, and u,v,w are complex numbers representing the vertices of two triangle such that they are similar, then prove that (a-c)/(a-b) =(u-w)/(u-v)

A man directly crosses a river in time t_1 and swims down the current a distance equal to the width of the river I time t_2 . If u and v be the speed of the current and the man respectively, show that : t_1 :t_2 = sqrt(v + u) : sqrt(v - u)) .