Torque physics lab report Essay Example

Torque physics lab report Essay Example Torque physics lab report Paper Torque physics lab report Paper The purpose of this experiment was to help understand torque by not only measuring it but also by manipulating and adjusting the weights experimentally. Procedure In order to perform all the procedures a few instruments were required a meter stick, a triple beam balance, suspension clamps and their stirrups, a knife edge, as well as weights of 50 and 100 grams and a spring scale. The meter stick was weighed (without the clamp), and its center of gravity was found (its not usually exactly at 50cm), the 6 clamps were weighed as well. For the first part the meter stick was put on 35cm and a 100g weight was adjusted until the center of balance was found, the position was recorded, this was than done with 150g and 50g. Once the values were recorded the weight of the bar was calculated and the average was found. For the next part of the experiment three weights were attached anywhere on the bar, the center one was adjusted till there was equilibrium and than the force was measured with a spring scale. The numbers were recorded and the weights of down and upward forces were measured as well as the clockwise and counter clockwise torques. For the last part of the experiment six clamps were arranged on the bar( with weights on them ) so that one was at 10cm and one at 90cm and the rest were spread in between , one end was supported by the knife edge and the other by the spring scale. The forced shown by the scale was recorded, the ends were than switched and the force was once again recorded. Calculations were than done to verify the sum of the torque was that of the reading on the spring scale as well as that the total sum of the weights was compared via calculation to the upward force shown. Data/Analysis Part I: Prep Part II: Calculating the weight of the meter bar by balancing torque (mb): (mc= mass of clamp, g = acceleration due to gravity) Table 1: Determination of Meter Weight by Balancing to Torque (Experimental) m= mass of weights (g) x= Clamp Position from knife edge (cm) mb= Weight of Meter Bar from Balancing Torque (g) Position on meter stick (cm) r= position from axis of rotation (m) (N*m)96 Questions: The motion of the rigid system will move up in the counter clockwise direction if the condition for equilibrium is not satisfied in which the spring has greater force. The opposite will happen if the meter bar and weights have a greater force than the spring. The same goes for the Torque. If the second condition for equilibrium is not satisfied and there is greater torque of the spring, the system will move in the counter clockwise motion and will move clockwise if the Torque is greater for the meter bar. The motion of the rigid system will move in the same fashion as described above if neither of the conditions for equilibrium are satisfied. If there are equal numbers of suspension clamps on each side of the support with the same weight, their weights can be omitted from the calculations because the weights can be factored out and be eliminated from the way the force and torque equations are set-up. Regardless, they should total to zero. When the center of gravity of the meter bar was determined in Part I, the bar was supported at a point coinciding with the center of gravity. If the clamp were to have been inverted, where the bar is supported at a point above the center of gravity, you wouldnt een be able to balance the meter bar because it is not in the center of gravity it would just be slack and hang down. Therefore you wouldnt even find the accurate position where it is level. This would have skewed the results, making inaccurate readings and calculations. In part IV, if the meter bar were to be held at an incline of 30 degrees angle above the horizontal by the spring balance, the spring balance reading would remain the same because the force of the spring is just m*g, which remains the same even if you change the angle. The mass and acceleration due to gravity remains constant. However, Torque changes (t=r(F*sin(? )) since angle comes into account. Figure: Conclusion In the study of this lab, torque was observed by measuring, manipulating, and adjusting the weights on the meter bar. The weight of the meter bar was found by experimentally calculating the torque. Comparing the actual weight of the meter bar and the experimental values, the percent error was only 5. 96%-14. %. This percent error is low enough to be negligible and to confirm the equation used for Part II. In Part III and IV, the forces acting on the meter stick are in the vertical direction. Since the meter stick was level, the angle was 180 degrees meaning the force acted on the axis on either side of the center of balance. The experiment should have observed that the net force and net torque acting on the meter stick is equaled to zero. However, experimental results show that the net force is not zero. The net torque is not zero as well. However, the net torque value approaches zero more than the experimental values do. Therefore, the torque equation may be confirmed in this experiment, but the force equation cannot because the values are too far from zero. This may be because the presence of error in this lab is high. Errors occurred in this lab are due to inaccurate measurements of position. It was difficult to keep the meter bar steady to find where the stick is level. Also, there may have been something wrong with the balance and springs because they are very old, rusted equipment and may not work as accurately as they did when they were new. Overall, we were able to understand the concept of torque, even if there were errors in our experiment.

Northrop P-61 Black Widow in World War II

Northrop P-61 Black Widow in World War II In 1940, with World War II raging, the Royal Air Force began seeking designs for a new night fighter to combat German raids on London. Having used radar to aid in winning the Battle of Britain, the British sought to incorporate smaller airborne intercept radar units into the new design. To this end, the RAF instructed the British Purchasing Commission in the US to evaluate American aircraft designs. Key among the desired traits were the ability to loiter for around eight hours, carry the new radar system, and mount multiple gun turrets. During this period, Lieutenant General Delos C. Emmons, the US Air Officer in London, was briefed on British progress relating to the development of airborne intercept radar units. He also gained an understanding of the RAFs requirements for a new night fighter. Composing a report, he stated that he believed the American aviation industry could produce the desired design. In the United States, Jack Northrop learned of the British requirements and began contemplating a large, twin engine design. His efforts received a boost later that year when a US Army Air Corps board chaired by Emmons issued a request for a night fighter based on the British specifications. These were further refined by the Air Technical Service Command at Wright Field, OH. Specifications General Length: 49 ft., 7 in.Wingspan: 66 ft.Height: 14 ft., 8 in.Wing Area: 662.36 sq. ft.Empty Weight: 23,450 lbs.Loaded Weight: 29,700 lbs.Maximum Takeoff Weight: 36,200 lbs.Crew: 2-3 Performance Maximum Speed: 366 mphRange: 610 milesRate of Climb: 2,540 ft./min.Service Ceiling: 33,100 ft.Power Plant: 2 Ãâ€" Pratt Whitney R-2800-65W Double Wasp radial engines, 2,250 hp each Armament 4 Ãâ€" 20 mm Hispano M2 cannon in ventral fuselage4 Ãâ€" .50 in M2 Browning machine guns in remotely operated, full-traversing upper turret4 Ãâ€" bombs of up to 1,600 lb. each or 6 Ãâ€" 5 in. HVAR unguided rockets Northrop Responds: In late October 1940, Northrops chief of research, Vladimir H. Pavlecka, was contacted by ATSCs Colonel Laurence C. Craigie who verbally detailed the type of aircraft they were seeking. Taking his notes to Northrop, the two men concluded that the new request from the USAAC was nearly identical to that from the RAF. As a result, Northrop produced the work done earlier in response to the British request and immediately had a head start over his competitors. Northrops initial design saw the company create an aircraft featuring a central fuselage suspended between two engine nacelles and tail booms. The armament was arranged in two turrets, one in the nose and one in the tail. Carrying a crew of three (pilot, gunner, and radar operator), the design proved unusually large for a fighter. This was necessary to accommodate the weight of the airborne intercept radar unit and the need for an extended flight time. Presenting the design to the USAAC on November 8, it was approved over the Douglas XA-26A. Refining the layout, Northrop quickly shifted the turret locations to the top and bottom of the fuselage. Subsequent discussions with the USAAC led to a request for increased firepower. As a result, the lower turret was abandoned in favor of four 20 mm cannon mounted in the wings. These were later repositioned to the underside of the aircraft, similar to the German Heinkel He 219, which freed up space in the wings for additional fuel while also improving the wings airfoil. The USAAC also requested the installation of flame arrestors on the engine exhausts, a rearrangement of radio equipment, and hard points for drop tanks. The Design Evolves: The basic design was approved by the USAAC and a contract issued for prototypes on January 10, 1941. Designated the XP-61, the aircraft was to be powered by two Pratt Whitney R2800-10 Double Wasp engines turning Curtiss C5424-A10 four-bladed, automatic, full-feathering propellers. As construction of the prototype moved forward, it quickly fell victim to a number of delays. These included difficulty obtaining the new propellers as well as equipment for the upper turret. In the latter case, other aircraft such as the B-17 Flying Fortress, B-24 Liberator, and B-29 Superfortress took priority in receiving turrets. The problems were eventually overcome and the prototype first flew on May 26, 1942. As the design evolved, the P-61s engines were changed to two Pratt Whitney R-2800-25S Double Wasp engines featuring two-stage, two-speed mechanical superchargers. Additionally, larger wider span flaps were used which permitted a lower landing speed. The crew was housed in the central fuselage (or gondola) with the airborne intercept radar dish mounted within a rounded nose in front of the cockpit. The rear of the central fuselage was enclosed with a plexiglass cone while the forward section featured a stepped, greenhouse-style canopy for the pilot and gunner.   In the final design, the pilot and gunner were situated toward the front of the aircraft while the radar operator occupied an isolated space towards the rear. Here they operated a SCR-720 radar set which was used to direct the pilot towards enemy aircraft. As the P-61 closed on an enemy aircraft, the pilot could view a smaller radar scope mounted in the cockpit. The aircrafts upper turret was operated remotely and targeting aided by a General Electric GE2CFR12A3 gyroscopic fire control computer. Mounting four .50 cal. machine guns, it could be fired by the gunner, radar operator, or pilot. In the last case, the turret would be locked in a forward-firing position. Ready for service in early 1944, the P-61 Black Widow became the US Army Air Forces first purpose-designed night fighter. Operational History: The first unit to receive the P-61 was the 348th Night Fighter Squadron based in Florida. A training unit, the 348th prepared crews for deployment to Europe. Additional training facilities were also used in California. While night fighter squadrons overseas transitioned to the P-61 from other aircraft, such as the Douglas P-70 and British Bristol Beaufighter, many Black Widow units were formed from scratch in the United States. In February 1944, the first P-61 squadrons, the 422nd and 425th, shipped out for Britain. Arriving, they found that the USAAF leadership, including Lieutenant General Carl Spaatz, were concerned that the P-61 lacked the speed to engage the latest German fighters. Instead, Spaatz directed that the squadrons be equipped with British De Havilland Mosquitoes. Over Europe: This was resisted by the RAF which wished to retain all available Mosquitoes. As a result, a competition was held between the two aircraft to determine the P-61s capabilities. This resulted in a victory for the Black Widow, though many senior USAAF officers remained skeptical and others believed the RAF had deliberately thrown the contest. Receiving their aircraft in June, the 422nd began missions over Britain the following month. These aircraft were unique in that they had been shipped without their upper turrets. As a result, the squadrons gunners were reassigned to P-70 units. On July 16, Lieutenant Herman Ernst scored the P-61s first kill when he downed a V-1 flying bomb. Moving across the Channel later in the summer, P-61 units began to engage manned German opposition and posted an admirable success rate. Though some aircraft were lost to accidents and ground fire, none were downed by German aircraft. That December, the P-61 found a new role as it helped defend Bastogne during the Battle of the Bulge. Using its powerful complement of 20 mm cannon, the aircraft attacked German vehicles and supply lines as it aided the besieged towns defenders. As the spring of 1945 progressed, P-61 units found enemy aircraft increasingly scarce and kill numbers dropped accordingly. Though the type was also used in the Mediterranean Theater, units there often received them too late in the conflict to see meaningful results. In the Pacific: In June 1944, the first P-61s reached the Pacific and joined the 6th Night Fighter Squadron on Guadalcanal. The Black Widows first Japanese victim was a Mitsubishi G4M Betty which was downed on June 30. Additional P-61s reached the theater as the summer progressed though enemy targets were generally sporadic. This led to several squadrons never scoring a kill for the duration of the war. In January 1945, a P-61 aided in the raid on the Cabanatuan prisoner of war camp in the Philippines by distracting the Japanese guards as the assault force neared. As the spring of 1945 progressed, Japanese targets became virtually nonexistent though a P-61 was credited with scoring the final kill of the war when it downed a Nakajima Ki-44 Tojo on August 14/15. Later Service: Though concerns about the P-61s performance persisted, it was retained after the war as USAAF did not possess an effective jet-powered night fighter. The type was joined by the F-15 Reporter which had been developed during the summer of 1945. Essentially an unarmed P-61, the F-15 carried a multitude of cameras and was intended for use as a reconnaissance aircraft. Redesignated F-61 in 1948, the aircraft began to be withdrawn from service later that year and was replaced by the North American F-82 Twin Mustang. Refitted as a night fighter, the F-82 served as an interim solution until the arrival of the jet-powered F-89 Scorpion. The final F-61s were retired in May 1950. Sold to civilian agencies, F-61s and F-15s performed in a variety of roles into the late 1960s.