Question

Two forces of 200 N each are applied to an object, such that they are at 140 degree from each other. what is the magnitude of the third force necessary to keep the object stationary? A satellite in a stable circular orbit around the Earth, travelling at 2.3 Times 10^2 km above the ocean has a period of The planet Venus has a period of 225 days in its orbit around the sun. The mean radius of its orbit is: The engine of a 1600 kg automobile exerts a constant force of 4800 N. How long does it take to change the speed of the car from 15.0 m/s to 23.0 m/s on a smooth, flat road? A skier starts down a 12 degree snow coverted incline from test. The coefficient of kinetic friction between the snow and the skis is 0.180. Calculate the acceleration of the skier down the incline What is the skier's speed after 5.0 s? A 0.80 kg object moves on a smooth horizontal plane such that its location is given by the coordinates x(t) = 2.5 cos 1.2t m at y(t) = 2.0 sin 1.2t m where t is in seconds and 1.2 is 1.2 rad/s. What is the velocity (magnitude and direction) of the object at t = 3.0 s? What is the force (magnitude and direction acting on the object at t = 3.0 s? A 75 kg rider on a 20 kg bicycle makes a turn of 20 m radius on a level ground at a speed of 36 km/h. Calculate the friction force. Calculate the total force exerted by the pavement. A child swings a 250 g weight on the end of a string in a horizontal circle, at a constant rate of 96 rev/min, while letting out the cord. If the string can support a maximum of 8.5N, Calculate the length of the cord when it breaks. If the child's hand is 1.25 m above the ground, how far from the child does the weight hit the ground when the cord breaks? Two equal spherical masses, separated by a distance of 10m, have a mutual gravitational attraction of 0.01 N. Calculate the mass of each sphere.

Answer 1

8)
Fnet of 2 given force = 200*cos 70 + 200*cos 70
= 137 N
so 3rd force should be equal in magnitude of Fnet but opposite in direction
F3 = 137 N
Answer: a

9)
mass of earth, M = 5.972*10^24 Kg
Radius of earth, R = 6371000 m
r = (6371000 + 230000) = 6601000 m
use:
G*M*m/r^2 = m*v^2/r
G*M/r = v^2
v^2 = (6.673*10^-11)*(5.972*10^24) / (6601000 )
v = 7769.9 m/s
T = 2*pI*r/v
= 2*pi*6601000 / 7769.9
= 5337.9 s
= 89 min
Answer: d

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