i. Two equal but unlike parallel forces having different lines of action produce




... Answer is (b) couple
 When Forces are equal and lines of action are the same then "NO Motion". When Forces are unequal and the line of action same then there will be Translational motion. When Forces are equal but the line of action is not the same they produce a Couple.


ii. The number of forces that can be added by head to the tail rule are:




... Answer is (d)  any number
 According to head to tail rule, we can add two or more vectors. So among the four options "any number " is the correct answer.


iii. The number of perpendicular components of a force is:




... Answer is (b) 2
The process of splitting of the vector into its components is called the Resolution of a vector. A Vector can split into two perpendicular components. Force is vector quantity So, The number of perpendicular components of a force is two. F = Fx + Fy


iv. A force of 10 N is making an angle of 30⁰ with the horizontal. Its horizontal component will be:




... Answer is (d) 8.7 N
 Given: F = 10 N and θ = 30⁰ The Horizontal Components of Force Fx = F cos θ Putting values we get F= 10 cos 30⁰ = 10 N x 0.866 = 8.66 N = 8.7 N


v. A couple is formed by:




... Answer is (d) two equal and opposite forces not in the same line
 By definition two equal but unlike (opposite) parallel forces having different lines of action (not in the same line) produce a couple.


vi. A body is in equilibrium when its:




... Answer is (d) acceleration is zero
According to the First Condition for Equilibrium "A body is said to be in equilibrium if the resultant of all forces acting body is zero" i.e. ΣF = 0. When ΣF = 0 means that acceleration is also zero.


vii. A body is in neutral equilibrium when it's centre of gravity: :




... Answer is (c) keeps its height if displaced
If a body remains in its new potion when disturbed from its previous position, it is said to be in a state of neutral equilibrium. In neutral equilibrium, the center of gravity remains at the same height.


viii. Racing cars are made stable by:




... Answer is (c) lowering their centre of gravity
 A body will be in stable equilibrium if the center of gravity is at the lowest position. So vehicles are made heavy at the bottom. This lowers their center of gravity and helps to increase their stability.



VIP Note: If you have Learned the above MCQs, then examine yourself by taking this Simple MCQS Quiz (Click here to play the Quiz)


 Unit-4: Turning Effects of Force

⇑
9th Class MCQs Quizzes LIST

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Unit-3    ⇚  9th Physics Content List    ⇛  Unit-5



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