- #1
hbk69
- 81
- 0
I have attempted the questions but have not managed to get the required answer because my knowledge of mechanics is very weak i have a problem visualising the scenario, could you please explain the steps behind each question to get to the final answer, thank you very much
I managed to find the answer to number 2) but do not understand what they were asking for when they said "without giving it any velocity components". I realized that usually i would use the horizontal component to find the time which i would then put in the y=1/2gt^2 formula to find the height, but here the height was already given as 100m so i just rearranged the equation to find the time. Once i found the time i put it in the x=vt formula to find the answer, x=vt usually would give you the range, so when they are saying no velocity components i am sure there is a link somewhere. Because the flyer has a horizontal speed? therefore does no velocity components mean that i find my answer in the same direction via x=vt which is the horixontal component of velocity.
Here are the problems.
1) A gun fires a shell which hits a target on the same level as the gun and is 1300m away. The muzzle velocity is 120 m/s. What angle of elevation to the horizontal was the barrel at? answer is (31 degrees)
2) A powered hang glider is moving at 15 m/s parallel to and 100m above flat ground. The flyer wishes to hit Dr. Mustoe, who is sitting on a park bench, with a bag of flour. He intends to release the bag without giving it any velocity components relative to the hang glider. How far away from the bench should he release the bag? Answer is (67.8m)
3) A 600kg car is moving on a level road at 30 m/s. How large a retarding force is required to stop it in a distance of 70m and what is the required coefficient of friction between tyre and road for this to be possible? Answer is (-3.86kN, 0.66)
4) A 20kg box sits on an incline of 300. If the coefficient of sliding friction between the box and incline is 0.3 what is the acceleration of the box down the incline? Answer is (2.35 m/s2)
Thank you very much
I managed to find the answer to number 2) but do not understand what they were asking for when they said "without giving it any velocity components". I realized that usually i would use the horizontal component to find the time which i would then put in the y=1/2gt^2 formula to find the height, but here the height was already given as 100m so i just rearranged the equation to find the time. Once i found the time i put it in the x=vt formula to find the answer, x=vt usually would give you the range, so when they are saying no velocity components i am sure there is a link somewhere. Because the flyer has a horizontal speed? therefore does no velocity components mean that i find my answer in the same direction via x=vt which is the horixontal component of velocity.
Here are the problems.
1) A gun fires a shell which hits a target on the same level as the gun and is 1300m away. The muzzle velocity is 120 m/s. What angle of elevation to the horizontal was the barrel at? answer is (31 degrees)
2) A powered hang glider is moving at 15 m/s parallel to and 100m above flat ground. The flyer wishes to hit Dr. Mustoe, who is sitting on a park bench, with a bag of flour. He intends to release the bag without giving it any velocity components relative to the hang glider. How far away from the bench should he release the bag? Answer is (67.8m)
3) A 600kg car is moving on a level road at 30 m/s. How large a retarding force is required to stop it in a distance of 70m and what is the required coefficient of friction between tyre and road for this to be possible? Answer is (-3.86kN, 0.66)
4) A 20kg box sits on an incline of 300. If the coefficient of sliding friction between the box and incline is 0.3 what is the acceleration of the box down the incline? Answer is (2.35 m/s2)
Thank you very much