# Machine Kinematics Questions and Answers – Friction of a Body Lying on a Rough Inclined Plane

This set of Basic Machine Kinematics Questions and Answers focuses on “Friction of a Body Lying on a Rough Inclined Plane”.

1. If the threads are cut on the outer surface of a solid rod, these are known as
c) helix
d) none of the mentioned

Explanation: The fastenings have screw threads, which are made by cutting a continuous helical groove on a cylindrical surface. If the threads are cut on the outer surface of a solid rod, these are known as external threads. But if the threads are cut on the internal surface of a hollow rod, these are known as internal threads.

2. If the threads are cut on the internal surface of a hollow rod, these are known as
c) helix
d) none of the mentioned

Explanation: The fastenings have screw threads, which are made by cutting a continuous helical groove on a cylindrical surface. If the threads are cut on the outer surface of a solid rod, these are known as external threads. But if the threads are cut on the internal surface of a hollow rod, these are known as internal threads.

3. The curve traced by a particle, while describing a circular path at a uniform speed and advancing in the axial direction at a uniform rate is known as
c) helix
d) none of the mentioned

Explanation: Helix is the curve traced by a particle, while describing a circular path at a uniform speed and advancing in the axial direction at a uniform rate. In other words, it is the curve traced by a particle while moving along a screw thread.

4. The distance from a point of a screw to a corresponding point on the next thread, measured parallel to the axis of the screw is the
a) helix
b) pitch
d) none of the mentioned

Explanation: Pitch is the distance from a point of a screw to a corresponding point on the next thread, measured parallel to the axis of the screw.

5. The distance, a screw thread advances axially in one turn is known as the
a) helix
b) pitch
d) none of the mentioned

6. The distance between the top and bottom surfaces of a thread is known as
b) pitch
d) none of the mentioned

Explanation: Depth of thread is the distance between the top and bottom surfaces of a thread (also known as crest and root of a thread).

7. The lead of a screw is equal to its pitch, it is known as
d) none of the mentioned

Explanation: If the lead of a screw is equal to its pitch, it is known as single threaded screw.

8. If more than one thread is cut in one lead distance of a screw, it is known as
d) none of the mentioned

Explanation: If more than one thread is cut in one lead distance of a screw, it is known as multi-threaded screw e.g. in a double threaded screw, two threads are cut in one lead length. In such cases, all the threads run independently along the length of the rod.

9. The nominal diameter of a screw thread is also known as
a) root diameter
b) minor diameter
c) outside diameter
d) none of the mentioned

Explanation: The core diameter of a screw thread is also known as inner diameter or root diameter or minor diameter.
The nominal diameter of a screw thread is also known as outside diameter or major diameter.

10. The core diameter of a screw thread is also known as
a) outside diameter
b) root diameter
c) major diameter
d) none of the mentioned

Explanation: The core diameter of a screw thread is also known as inner diameter or root diameter or minor diameter.
The nominal diameter of a screw thread is also known as outside diameter or major diameter.

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