Applied Mechanics And Graphic Statics - Study Mode

[#346] The resultant of two forces P and Q is R. If Q is doubled, the new resultant is perpendicular to P. Then,
Correct Answer

(B) Q = R

[#347] Power developed by a torque, is
Correct Answer

(D) All the above

[#348] The shape of a suspended cable for a uniformly distributed load over it is
Correct Answer

(B) Parabolic

Explanation

Solution: The correct answer is B: Parabolic . Here's why: * Uniformly Distributed Load: This means the load is spread evenly across the horizontal span of the cable (like the weight of a bridge deck hanging from the cable). * Parabolic Shape: When a cable is subjected to a uniformly distributed load horizontally , the cable takes the shape of a parabola. This shape ensures that the tension in the cable is efficiently distributed to support the load. * Catenary Shape (Why it's not the answer): A catenary curve is the shape a cable takes when it's only supporting its own weight (or a load distributed along the length of the cable itself , not horizontally). Think of a cable hanging freely between two points. * Other Options: Circular and Cubic Parabola shapes are not naturally formed by suspended cables under common loading conditions like a uniform distributed load.

[#349] Pick up the correct statement from the following. A rubber ball when strikes a wall rebounds but a lead ball of same mass and velocity when strikes the same wall, falls down
Correct Answer

(B) Change in momentum suffered by lead ball is less that of rubber ball

Explanation

Solution: Let's break down this question step-by-step! The key here is understanding what happens to momentum when each ball hits the wall. Momentum is a measure of mass in motion. Momentum depends on two things: how heavy something is (mass) and how fast it's moving (velocity). The question tells us both balls have the same mass and are moving with the same velocity initially. This means they start with the same momentum. Now, consider what happens after they hit the wall: - The rubber ball rebounds (bounces back) . This means its velocity changes direction, and its momentum also changes direction. - The lead ball falls down . This means it essentially stops
its velocity becomes zero. So, its momentum becomes zero. Change in momentum is calculated by: Final momentum - Initial momentum. For the rubber ball , the final momentum is in the opposite direction to its initial momentum, so the change is significant (close to double the initial momentum). For the lead ball , the final momentum is zero, so the change is equal to the initial momentum. Therefore, the rubber ball undergoes a much greater change in momentum than the lead ball. Let's look at the options: Option A: Rubber and lead balls undergo equal changes in momentum - Incorrect . We've just shown that the rubber ball's change in momentum is larger. Option B: Change in momentum suffered by lead ball is less that of rubber ball - Correct . This is what we concluded above. Option C: Momentum of rubber ball is less than that of lead ball - Incorrect . Initially, they have equal momentum and the change in momentum is what differs. Also it is talking about the current scenario after striking not the initial one. Option D: None of these - Incorrect . Option B is correct. So, the correct answer is Option B.