wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

A man of 2 m height walks at a uniform speed of 6 km/h, away from a lamp post of 6 m height. The rate at which the length of his shadow increase is


A

2 km/h

No worries! We‘ve got your back. Try BYJU‘S free classes today!
B

1 km/h

No worries! We‘ve got your back. Try BYJU‘S free classes today!
C

3 km/h

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D

6 km/h

No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C

3 km/h


Finding the rate at which the length of the shadow will increase:

Let the length of the shadow be ‘y’ m and the distance from the lamp post and the man be ‘x’ m.

AB=6cmCD=2cm

By the theorem of similar triangles,

ABBE=CDDE6x+y=2y6y=2x+2yx=2ydxdt=2dydt6=2dydtdxdt=6dydt=3km/h

The rate at which the length of his shadow increase is 3 km/h.

Hence, the correct option is (C).


flag
Suggest Corrections
thumbs-up
2
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Rate of Change
MATHEMATICS
Watch in App
Join BYJU'S Learning Program
CrossIcon