Tag Archives: velocity

I stink at science, can u help me with these problems i have on webassign.?

Posted on May 7, 2012 by admin| 1 Comment

An ice sled powered by a rocket engine starts from rest on a large frozen lake and accelerates at +13.0 m/s2. At tl = 2.8 s the rocket engine is shut down and the sled moves with constant velocity v. At the 3800 m mark, the sled begins to accelerate at -7 m/s2. Find v to help answer the following questions.
(a) What is the final position of the sled when it comes to rest?
______m
(b) How long after it begins decelerating does it take for the sled to come to rest?
_______ s ————Next question———–

A model rocket is launched straight upward with an initial speed of 75.0 m/s. It accelerates with a constant upward acceleration of 2.0 m/s2 until its engines stop at an altitude of 150 m.
(a) What is the maximum height reached by the rocket?
_____m
(b) How long into the flight does the rocket reach maximum height?
______s
(c) How long is the rocket in the air?
______ s

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HELP! Just some little algebra problem I can’t figure out today.?

Posted on April 12, 2012 by admin| 1 Comment

Here it is: A model rocket is fired straight up from groung level with an initial velocity of 100ft per second. the height “h” of the rocket after “t” seconds in flight if given by h=-16t(squared) + 100t.
(a) rewrite the equation for h by factoring the right hand side if the equation above.
(b)At what times ‘t’ will the rocket be on the ground?(This is especially good to know if you are standing at the firing location and do not want to get hit when the rocket comes back down.)
Please help!!!!! Sort of explain too. 10 points for who ever makes sense!

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math???????????????

Posted on April 8, 2012 by admin| 3 Comments

a model rocket is launched from a platform 2 feet above the ground with an initial upward velocity of 100 feet per second. After how many seconds will the rocket hit the ground?

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I am very confused can someone please help?

Posted on February 26, 2012 by admin| 4 Comments

Mr. Alim’s science class launched a toy rocket from ground level with an initial upward velocity of 60 ft per second. The height ‘h’ of the rocket in feet above the ground after ‘t’ seconds is modeled by the equation h=60t-16t^2. How long was the rocket in the air before it returned to the ground?

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A rocket accelerates by burning its onboard fuel, so its mass decreases with time. Suppose the initial mass of

Posted on February 13, 2012 by admin| 1 Comment

A rocket accelerates by burning its onboard fuel, so its mass decreases with time. Suppose the initial mass of the rocket at liftoff (including its fuel) is m, the fuel is consumed at rate r, and the exhaust gases are ejected with constant velocity, ve (relative to the rocket). A model for the velocity of the rocket at time t is given by the equation below where g is the acceleration due to gravity and t is not too large.

v(t)=-gt- ve(ln((m-rt)/m))

If g = 9.8 m/s^2, m = 30000 kg, r = 155 kg/s, and ve = 3000 m/s, find the height of the rocket one minute after liftoff.

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A model rocket is fired vertically upward from rest. Its acceleration for the first three seconds is a(t) = 60

Posted on February 12, 2012 by admin| 1 Comment

A model rocket is fired vertically upward from rest. Its acceleration for the first three seconds is a(t) = 60t at which time the fuel is exhausted and it becomes a freely “falling” body. Fourteen seconds later, the rocket’s parachute opens, and the (downward) velocity slows linearly to -18 ft/s in 5 s. The rocket then “floats” to the ground at that rate.
(a) Determine the position function s and the velocity function v (for all times t).
(b) At what time does the rocket reach its maximum height?
What is that height?
(c) At what time does the rocket land?

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Newtons first and second law. What are the components of the force and what is its magintude.?

Posted on January 19, 2012 by admin| 2 Comments

To model a spacecraft, a toy engine is securely fastened to a large puck, which can glide with negligible friction over a horizontal furface, taken as teh xy plane. The 7.0kg puck has a velocity of 2.00i m/s at one instant. Eight seconds later, its velocity is to be (5.00i + 7.00j)m/s. Assuming the rocket engine exerts a constant total horizontal force, find the components of the force. Find its magniutde.

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