Answer:
a) m = 69.0 kg
b) release some gas in the opposite direction to the astronaut's movement
Explanation:
a) Let's use Newton's second law
F = m a
m = F / a
m = 60.0 / 0.870
m = 69.0 kg
b) when we exert a force on the astronaut it acquires a momentum po, as the astronaut system plus spacecraft is isolated, the momentum is conserved
p₀ = p_f
m v = M v '
v ’= 
so we see that the ship is moving backwards, but since the mass of the ship is much greater than the mass of the astronaut, the speed of the ship is very small.
One method to avoid this effect is to release some gas in the opposite direction to the astronaut's movement so that the initial momentum of the astronaut plus the gas is zero and therefore no movement is created in the spacecraft.
Answer: C. electricity and magnetism
Explanation:
Answer:
(D) 42.4N
Explanation:
Since the frame is at rest, the net force acting on it must be 0. There are three forces acting on it: the gravity and the opposing forces of the two cables.
Since the gravity is a vertical force, we are only interested in the vertical components of the remaining forces. The net force equation is
F_net = 0 = F_g -2 * F_y
The vertical force of one cable (using the information in the drawing) is:
F_y = 30N * sin 45 deg = 21.21N
Now the weight can be determined:
0 = F_g - 2 * F_y
F_g= 2 * F_y = 2 * 21.21N = 42.4N
The weight of the frame is about 42.4N.
A revolution equals 2*pi radians.
As the wheel rotates half every 4 seconds, then it means that it rotates half revolution.
Thus, the angular velocity of the wheel is given by:
w = (pi) / (4) = 0.79 rad / sec
answer
The wheel's angular velocity is 0.79 rad / sec
Answer:
Explanation:
Conservation of angular momentum
The MGR originally has momentum
L = 100(3.0) = 300 kg•m²/s²
The child can be thought of as a point mass with I = mr²
When she jumps onto the rim of the MGR
300 = (100 + 22(2.0²)ω
ω = 300 / 188 = 1.5957... 1.6 rad/s
As she moves toward the center of the MGR, her moment of inertia goes to zero as her radius goes to zero.
The angular velocity when she reaches the center will again be 3.0 rad/s
