A hailstone with a mass 10g falls a distance of 100m to the ground which it hits with a velocity of 30m/s. How much work have been done by air resistance (g=9.8m/s)
Answers
Answer:
0.53 Joules
Explanation:
Firstly, u must be aware of these equations, Work done=(mass)(gravitational field strength)(height)//(Force)(displacement); Force=(mass)(acceleration); g=9.8m/(s)squared
(final velocity)squared=(initial velocity)squared + 2(acceleration)(displacement)
After that, understand the question. Note that the air resistance is NOT negligible so it will have a significant effect on the acceleration and final velocity of the hailstone.
Calculate the work done without air resistance. (applying this equation --> Work done=(mass)(gravitational field strength)(height) ) You should get the answer of 0.98 Joule.
Then, calculate the acceleration and work done of hailstone with air resistance. Given that the final velocity of hailstone before hitting the ground is 30m/s and assuming its initial velocity is 0 m/s as the question used the word 'fall'. You should get the answer of 4.5 m/s2 and 0.45 Joule. (by applying the equations--> Work done=(mass)(gravitational field strength)(height)//(Force)(displacement); Force=(mass)(acceleration); g=9.8m/(s)squared
(final velocity)squared=(initial velocity)squared + 2(acceleration)(displacement) )
Finally, minus the work done of hailstone without by that of with air resistance to find the work done of AIR RESISTANCE only (0.98-0.45=0.53 Joule)
Hope that helps ;)