#46 an attacker d1 = 100m d3 50m To get a for d3 formula: -vo + at -20 + a(5) di

Question

#46 an attacker

d1 = 100m d3 50m To get a for d3 formula: -vo + at -20 + a(5) divide 5 by both sides to get a alone, a =-4m/s^2 100m+400m+50m: 550m / 35s 15.7m/s 46) An attacker at the base of a castle wall 3.65 m high throws a rock straight up with speed 7.40 m/s from a height of 1.55 m above the ground. (a) Will the rock reach the top of the wall? (b) If so, what is its speed at the top? If not, what initial speed must it have to reach the top? (c) Find the change in speed of a rock thrown straight down from the top of the wall at an initial speed of 7 40 m/s and moving between the same two points. (d) Does the change in speed of the downward moving rock agree with the magnitude of the speed change of the rock moving upward between the same elevations? (e) Explain physically why it does or does not agree 51) A ball is thrown directly downward with an initial speed of 8.00 m/s from a height of 30.0 m After what time interval does it strike the ground? Vi = 8m/s d= 30m a= 9.8m/s^2 30-(8)t+ ½(9.8)t"2 -30 to other side to make equation = to 0 4.9m2+8t-30 = 0 USE QUADRATIC FORMULA tb+-sqrtb 2-4ac/2a

Explanation / Answer

H = 3.65 m , u =7.4 m/s, h =1.55 m

(a) from kinematic equaitons

v^2 -u^2 =2as

g =9.8 m/s^2

7.4*7.4 = 2*9.8*(d-1.55)

d = 4.344 m

dis greater than wall height(3.65m)

yes, it rock will reach the top of the wall.

(b) from kinematic equation

v^2 -u^2 = 2as

v^2 - (7.4)^2 = - (2*9.8*(3.65-1.55))

velocity at top of the wall v = 3.69 m/s

(c) s = 3.65 m, u = 7.4 m/s

from kinematic eqaution

v^2 -u^2 =2as

v^2 -(7.4*7.4) =(2*9.8*3.65)

v =11.24 m/s

change in speed v -u = 11.24 - 7.4 = 3.84 m/s

(d) Yes

(e) while moving down velocity increased and acceleration equal to accleration due to gravity

while moving up velocity decreased and acceleration equal to accleration due to gravity

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.