Question

A 60.0-kg projectile is fired at an angle of 30.0° above the horizontal with an initial speed of 124 m/s from the top of a cliff 144 m above level ground, where the ground is taken to be y = 0. (a) What is the initial total mechanical energy of the projectile? (Give your answer to at least three significant figures.) (b) Suppose the projectile is traveling 87.9 m/s at its maximum height of y = 304 m. How much work has been done on the projectile by air friction? (c) What is the speed of the projectile immediately before it hits the ground if air friction does one and a half times as much work on the projectile when it is going down as it did when it was going up? m/s

Answer 1

KE PE a Total machanical Garage energy The mos is at a hought of mm intially So, per migh box dise x10 - 86463 Initial velocity: 127 ms Total mechanial energy 864 Wt 461276 = 547.68 k] Indtil KE. mu?: *x60x124124 xbox 124 x124 - 46128 kJ 30ym (6) Cowen maumum height PE of Me height righ - 60x10 x 304 • 1824. Speed at maximum height = 8), mis height 4x60x1134872 • 231.8 kJ Let the work done by the friction be x 3 Then from anseuntion et energy .we hat Initial mechannel Mechand master mechanical I energy at mainen height + Work done 511-48W]: 1246] 1 231.26) 41. by friction le 133 48 RJ Hence work done by the fuction is 133 84 ]

1) When the ball reaches the ground, its PE = mgh - 60410XD Cuven work due to an fruction 31 151-15 X 133-34 200 W speld when it rich the ground be v Now, let the sold Ketow's įxbonus 3ové Now, from the conseruntion at mechanical energy we have Mechanical energy of at mas beight E ground + Work done by the PEA + KE al the al ground friction 182 441 + 231 0 + 30V + 200 t W] 3ov: 213.44 V 7 ve San 267 mis >
If you have any doubt then mention in the commant.