wiz-icon
MyQuestionIcon
MyQuestionIcon
3
You visited us 3 times! Enjoying our articles? Unlock Full Access!
Question

A small block of mass of 0.1 kg lies on a fixed inclined plane PQ which makes an angle θ with the horizontal. A horizontal force of 1 N acts on the block as shown in the figure. The block remains stationary if (take g=10 m/s2)

A
θ=45
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
θ>45, and a frictional force acts on the block towards P
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
θ>45, and a frictional force acts on the block towards Q
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
θ<45, and a frictional force acts on the block towards Q
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C θ>45, and a frictional force acts on the block towards Q
From the FBD of small block, while at rest
Along the plane,
sin(90θ)=mgsinθfs
1cosθ=mgsinθμR ... (1)
Perpendicular to the plane,
R=mgcosθ+cos(90θ)
R=mgcosθ+1sinθ ... (2)
From (1) & (2) we get
cosθ=mgsinθμ×mgcosθμsinθ
cosθ+μsinθ=mg(sinθμcosθ)
cosθ+μsinθsinθμcosθ=mg1=1
For a frictionless surface μ=0
θ=45

Since for θ=45 no friction is required to keep the block stationary, therefore as the value of θ becomes more than 45 , the component of gravitational force (mgsinθ) increases and friction acts towards Q to keep the block stationary.


flag
Suggest Corrections
thumbs-up
13
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Rubbing It In: The Basics of Friction
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon