Question

A spherical non-rotating planet (with no atmosphere) has mass m1= 4 ×1024 kg and radius r1= 5000 km. A projectile of mass m2≪m1 is fired from the surface of the planet at a point A with a speed vA at an angle α=30∘ with respect to the radial direction. In its subsequent trajectory the projectile reaches a maximum altitude at point B on the sketch. The distance from the center of the planet to the point B is r2=(5/2)r1. Use G=6.674×10−11 kg−1m3s−2.

What is the initial speed vA of the projectile? (in m/s)

Answer 1

http://web.mit.edu/8.01t/www/materials/InClass/IC_Sol_W13D1-8.pdf

Answer 2

Hi Elena, The equation I used for to solve for Va is
sqrt((5/4)*(G*m_1/r_1). It came out wrong. Is this the correct equation. Thanks.

Answer 3

equation is fine..check your parenthesis write ti down this way Sqrt(5*G*m1/4*r1)

Answer 4

@ Greco u done for this q8??? need help A ruler stands vertically against a wall. It is given a tiny impulse at θ=0∘ such that it starts falling down under the influence of gravity. You can consider that the initial angular velocity is very small so that ω(θ=0∘)=0. The ruler has mass m= 100 g and length l= 15 cm. Use g=10 m/s2 for the gravitational acceleration, and the ruler has a uniform mass distribution. Note that there is no friction whatsoever in this problem. (See figure)

(a) What is the angular speed of the ruler ω when it is at an angle θ=30∘? (in radians/sec)

ω=

unanswered
(b) What is the force exerted by the wall on the ruler when it is at an angle θ=30∘? Express your answer as the x component Fx and the y component Fy (in Newton)

Fx=

unanswered
Fy=

unanswered
(c) At what angle θ0 will the falling ruler lose contact with the wall? (0≤θ0≤90∘; in degrees) [hint: the ruler loses contact with the wall when the force exerted by the wall on the ruler vanishes.]

θ0=
i got a) only !

Answer 5

@kumar can you explain a)

Answer 6

for a) use this formula
w=sqrt(3*g(1-costheta)/L)

Answer 7

any one got b and c help plz!