The following force vectors act on an object 25 Newtons at 45 degree north of ea

Question

The following force vectors act on an object 25 Newtons at 45 degree north of east and its 50 Newtons at 30 degree south of east. Which of the following represents the magnitude of the resultant its angle relative to the easterly direction? 55.6 Newtons -7.50 deg 61.4 Newtons -6.85 deg 75.0 Newtons 15 deg 35.7 Newtons 0 deg 61.4 Newtons 21.8 deg. A jet airliner moving at 500 mph due east moves into a region where the wind is blowing at 120 mph in a direction 30 degree north west. What is the new velocity and direction of the aircraft? 400 mph, 8 deg N of E 607 mph, 5.67 deg N of E 620 mph, 7.10 deg N of E 380 mph, 150 deg 550 mph, 6.22 deg N of E. A ball is thrown up in the air with an initial velocity of 34.3 m/s upward. How long does take the ball to return to the ground? 12.3 s 1.98 s 7.0 s 2s 1. 9 s A runner of mass 56.1 kg starts from rest and accelerates with a constant acceleration of 123 m/s^2 until she reaches a velocity of 5.1 m/s. She then continues running at this constant velocity. How long in seconds does the runner take to travel 123 m? 24.12 20 26.19 22 04 28.32 A) B) C) D) E) A car slows down from a speed of 30 m/s to a speed of 12 m/s over a distance of 280 m. How long does this take, assuming constant acceleration? 34.2 sec 25 sec 21.9 sec 17, 7 sec 13.3 sec If the velocity of an object is given by V = 3r^2 - t + 2, when x0 = 8, what is its displacement after 3 seconds? 137.3 319 129.3 230 145.8 Omar throws a rock down with speed 12 m/s from the top of a tower. The rock hits the ground after 2.0 s. What is the height of the tower ? (air resistance is negligible) 72 m 20 m 44 m 63 m Note the expression: y = x^2.Which statement is most consistent with this expression? if y doubles, then x quadruples if x doubles, then y doubles if x doubles, then y quadruples y is greater than x if x triples, then y doubles

Explanation / Answer

9)

10)

The east component is 500mph + 120mph*cos(30) = 603.92 mph
The north component is 120mph*sin(30) = 60mph

So we have V = sqrt(603.92^2 + 60^2) = 606.89mph at = arctan(60.0/603.92) = 5.67o north of east

ans....option B)

11)

Vf = Vi - g*delta t
zero = 34.3 - 9.8*delta t
9.8*delta t = 34.3
delta t = 34.3 / 9.8 = 3.50 s (this is upward)
time in air = 2*delta t
time in air = 2x3050 = 7.00 s....................option C)

15.

x = (3/5)t^5 -(5/2)t^2 +2t + 8

so at t=3s x=  (3/5)3^5 -(5/2)3^2 +2x3 + 8

x = 137.3 ......................option A)

16.)

The rock accelerates because of gravity. So the building is higher than 2*12=24m. So answers (a) and (e) are wrong.

The acceleration of the rock is the same as the Earth's gravity (no mass of the rock is needed, since all objects fall at the same speed, regardless of their mass):
a = g = 9.81m/s^2 (let's say 10m/s^2)
By integrating over time, you get the velocity:
v = g*t + v0, where v0=12m/s
By integrating again, you get the height:
h = (1/2)*g*t^2 + v0*t
We know g=10m/s^2, t=2s and v0=12m/s
h = 0.5*10*2^2 + 12*2 = 20 + 24 = 44

The building is 44m high. The answer is (c)

17)

c) if x double then y quadrupole

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