Engineering Mechanics - Study Mode

[#81] In ideal machines
Correct Answer

(B) Mechanical advantage is equal to velocity ratio

Explanation

Solution: Option A: Mechanical advantage is greater than velocity ratio In an ideal machine, there are no energy losses due to friction or other resistances. Therefore, the mechanical advantage cannot be greater than the velocity ratio because that would imply the machine is creating additional energy, which is impossible in an ideal system. Option B: Mechanical advantage is equal to velocity ratio In an ideal machine , the mechanical advantage (MA) is equal to the velocity ratio (VR) because all the input energy is fully transmitted to the output without any losses. This equality holds true as there are no inefficiencies in an ideal machine. Option C: Mechanical advantage is less than velocity ratio In real machines, due to energy losses, the mechanical advantage is often less than the velocity ratio. However, in ideal machines, where no losses are assumed, the mechanical advantage should equal the velocity ratio, not be less than it. Option D: Mechanical advantage is unity While mechanical advantage can be unity in specific scenarios, it is not a general characteristic of all ideal machines. An ideal machine’s mechanical advantage will match the velocity ratio, but the value is not limited to unity. Conclusion: The correct answer is Option B: Mechanical advantage is equal to velocity ratio . In an ideal machine, mechanical advantage equals the velocity ratio due to the absence of energy losses.

[#82] In determining stresses in frames by methods of sections, the frame is divided into two parts by an imaginary section drawn in such a way as not to cut more than
Correct Answer

(B) Three members with unknown forces of the frame

[#83] A trolley wire weighs 1.2 kg per meter length. The ends of the wire are attached to two poles 20 meters apart. If the horizontal tension is 1500 kg find the dip in the middle of the span
Correct Answer

(C) 4.0 cm

[#84] Coplanar non-concurrent forces are those forces which __________ at one point, but their lines of action lie on the same plane.
Correct Answer

(B) Do not meet

[#85] Which of the following do not have identical dimensions?
Correct Answer

(D) Moment of a force and angular momentum