Find out also the loss of energy through impact, Mechanical Engineering

Assignment Help:

Find out also the loss of energy through impact:

Example

1. A bullet weighing 0.1 newton horizontally fired with a velocity of 80 metres/sec hits a wooden block, weighing 0.9 Newton. This penetrates into the block through a distance of 8 cms while the latter is held firmly in a clamp. Find out the average resistance offered by the wooden block to the penetration of the bullet.

2. If the block were free to move on a smooth horizontal plane, find out the penetration of the bullet. Find out also the loss of energy through impact.

Solution

Consider the average resistance of wooden block to the penetration of the bullet be R Newtons.

 (i)        While block is held fixed in a clamp, the whole of Kinetic Energy (KE) of the bullet is lost in doing work of penetration of 8 cm (that means 0.08 metres).

∴ Work done by R = KE of bullet

R × 0.08 = (0.1 × 80 × 80) / (2 × 9.8)

∴ R = 408.16 N.

 (ii)       While the block is free to move horizontally, Consider Vc be the common velocity after impact

∴ (0.1 + 0.9) × Vc / g = (0.1 × 80) /g

∴ Vc  = 8 metres / sec .

Entire KE of the combined mass after impact

=  1 × 82 /2 × 9.8      = 3.27 N. m.                             ---------- (1)

Total KE of the system before impact

= (0.1 × 80 × 80 )/2 g   = 32.65 N-m-------------- (2)

∴ Energy lost in impact (i.e. in causing penetration)

                        = (1) - (2) = 29.38 N.m         ------------ (3)

Neglecting other losses like heat, sound etc. during the process of penetration, if we assume that resistance R absorbs this change in KE given in Eq. (3).

             R × l = 29.38

∴ l = 29.38 /408.16     = 0.072 m.

 Note down that penetration of 7.2 cm under case (ii) is less than that case (i).

N. B.    If the wooden block is free to move on a horizontal surface, it shall continue to move along a constant velocity Vc. Though, if R′ is a resistance offered so that it comes to rest through a distance s′, then

R′ × s′ = KE of the combined mass after the impact.

= 1 ×( Vc)2 / 2 g


Related Discussions:- Find out also the loss of energy through impact

Find the maximum shear stress - stepped circular bar, Find the maximum shea...

Find the maximum shear stress - stepped circular bar: A stepped circular bar ABC 4 m long fixed at one of the end 'A' is subjected to a torque of 10 kN-m. If the portion AB is

Find out horizontal and vertical components of hinge force, Find out horizo...

Find out horizontal and vertical components of hinge force: The frame shown in Figure is supported by a hinge at E and a roller support at D. Find out horizontal and vertical

What is a clay-characteristics , 1.  What is a soil in an engineering conte...

1.  What is a soil in an engineering context? Define. 2.  (a)  What is a clay? (b) What are the major properties and characteristics of clay? Discuss. (c)  Define the term

Handling tools and equipment for skid, Q. Handling tools and equipment for ...

Q. Handling tools and equipment for skid? Lifting or pulling and provisions for transportation of skid shall be in accordance with GS-904-0103, other relevant parts of contract

Advantages-disadvantages of transparent polymeric, (a) List several advanta...

(a) List several advantages and disadvantages of using transparent polymeric materials for eyeglass lenses. (b) Cite four properties (in addition to being transparent) that are

What is the mean of off time, Q.What is the mean of Off time? It is the...

Q.What is the mean of Off time? It is the interval from the end of the hold time to the beginning of the squeeze time for the next (resistance) welding cycle. In automatic m

Explain rake angle - angles of a drill, Explain Rake angle - Angles of a dr...

Explain Rake angle - Angles of a drill It is also known as helix angle .It is the angle formed between a plane containing the drill axis and the leading edge of the land. It c

Maintenance requirement at storage tanks, Q. Maintenance requirement at sto...

Q. Maintenance requirement at storage tanks? Little maintenance is required at storage tanks; sometimes access is required for equipment used to remove accumulated solids (this

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd