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galina1969 [7]
2 years ago
12

A 12,000-kg lunar landing craft is about to touch down on the surface of the moon, where the acceleration due to gravity is 1.6

m/s2. At an altitude of 158 m the craft's downward velocity is 16.9 m/s. To slow down the craft, a retrorocket is firing to provide an upward thrust. Assuming the descent is vertical, find the magnitude of the thrust needed to reduce the velocity to zero at the instant when the craft touches the lunar surface. In newtons.
Physics
1 answer:
grin007 [14]2 years ago
6 0

Answer:

F = 8354.05 N

Explanation:

m = 12000 Kg

g = 1.6 m/s²

y = 158 m

vi = 16.9 m/s

vf = 0 m/s

F = ?

We can apply the following equation

F – W = - m*a    ⇒    F = W - m*a     ⇒   F = m*g - m*a = m*(g-a)     (I)

As a is an unknown magnitude, we can use the formula

vf² = vi² – 2*a*y  ⇒   0 = vi² – 2*a*y   ⇒   a = (vi²) / (2*y)

then  

a = (16.9 m/s)² / (2*158 m) = 0.9038 m/s²

Now we use the equation I

F = (12000 Kg)* (1.6 m/s² - 0.9038 m/s²) = 8354.05 N

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Answer:

v_avg = 2.9 cm/s

Explanation:

The average velocity of the object is the sum of the distance of all its trajectories divided the time:

v_{avg}=\frac{x_{all}}{t}

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Then, x_all = 150cm + 140cm = 290cm

The average velocity is, for t = 100s

v_{avg}=\frac{290cm}{100s}=2.9\frac{cm}{s}

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A cart is driven by a large propeller or fan, which can accelerate or decelerate the cart. The cart starts out at the position x
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Answer:

The acceleration of the cart is 1.0 m\s^2 in the negative direction.

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Where Vf is the final velocity of the cart, Vi is the initial velocity of the cart, a the acceleration of the cart and x the displacement of the cart.

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x = 12.5 - 0

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A screwdriver is used to pry the lid off a paint can. The resistance arm is 0.5 cm long and the effort arm is 20 cm long. What i
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Answer:

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A seaplane flies horizontally over the ocean at 50 meters/second. It releases a buoy, which lands after 21 seconds. What's the v
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where h is the initial heigth of the buoy when it is released from the plane. At the time t=21 s, the buoy reaches the ground, so y(21 s)=0. If we substitute these two numbers inside the equation, we can find the value of h, the vertical displacement from the plane to the ocean:
0=h- \frac{1}{2}gt^2
h= \frac{1}{2}gt^2= \frac{1}{2}(9.81 m/s^2)(21 s)^2=2163 m
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