can u help with this physics q?

Question

a runaway truck with failed brakes is moving downgrade at 102 km/h just before the driver steers the truck up a frictionless emergency escape ramp with an inclination of = 10°. The truck's mass is 1.2 x 104 kg. (a) What minimum length L must the ramp have if the truck is to stop (momentarily) along it? (Assume the truck is a particle). What is the minimum length L if (b) the truck's mass is decreased by 21% and (c) its speed is decreased by 34%?

thanks very much

Answer 1

v = 102 * 3600/1000 metres/second

Conservation of energy: when it reaches a stop all the kinetic energy (m*v^2/2) will have been converted to potential energy (m*g*h)

Find h (the vertical height gained) then length of the ramp L is just h/sin(10)

Not his day is it? Brakes failed and some nut designs a frictionless escape ramp!

Answer 2

The truck is moving horizontally as it approaches the slope, and parallel to it, when it is on the slope. It is motion parallel to the slope with which you are concerned. The acceleration due to gravity, g, may be considered to have a component acting perpendicular to the slope, and a component acting parallel to the slope. From trigonometry, the component of g acting down a slope of angle 'z', = g(sin z). So, where z is 10 degrees, sine of z = sine of 10 = 0.174
So, if g = 9.8 ms^-2, gsinz = 9.8 x 0.174 = 1.7 ms^-2.

This can then be used as the value 'a', the acceleration, in the equation, v^2 = u^2 + 2as,
where v = final velocity (0, since the truck comes to a stop).
u = intitial velocity (102 km/h = 28.3 ms^-1)
a = gsinz = 1.7 ms^-2. Actually, -1.7 ms^-2, because this is decelleration, not acceleration)
s = L, the distance tavelled.

Substitute in these numbers gives:
0 = 28.3^2 + 2 x (-1.7) x L
Simplify and rearrange:
802.8 = 3.4L, therefore:
L = 802.8/3.4 = 236.1 m.

b). The force of gravity acts in proportion to the mass of the object, so altering its mass will have no effect. (Just as a cannon ball and a tennis ball fall at the same rate).

c) Decreasing its speed by 34% gives it a new speed of
0.66 x 28.3 = 18.7 ms^-2. Use this as the value of 'u' in the equation above, to solve this question.

Answer 3

Physics (also reffered to as fizziks or fyzix) is a popular religion with a large following, although we all know Physics doesn't work. Although adherents can be found throughout the world, it is most devoted to by the socially unpopular educated classes in Western Europe and French Polynesia. Based largely on Christianity, with Albert Einstein replaced as Christ, and Niels Bohr seen as the Father, most scholars agree that the religion began with the publication of Observations upon the Prophecies of Daniel and the Apocalypse of St John by Isaac Newton in 1733.

The Max "Steven" Weinberg's paradox, whether the graviton, or the wave it produces, should be considered as the immaculate endorser, and the immobile object, or not, has divided the Physicist faith is divided into several sects, including The True Church of Natural Philosophiae founded by charismatic preacher George W. Bush, and the Real and Living Brotherhood of Particle Phenomenology, lead for decades by the iron willed dictator, Oprah Winfrey.
Famous constants
Universal Gravitational Constant (.98 x 10^1)
Speed of dark (900000000000000 x 10 ^ -5)
Speed of gossip (9000000000000000 x 10 ^999 ^999 ^999)
Speed of bad news (really really big, like bigger than this Really Big Tree)
Pi. (3)
[edit] Not so constants
The amount of constants.
Variables that are not constant.
Not constant variables.
The speed of sound, light, pseudogravity, and antipseudogravity.
[edit] Breaking the Physics
So far only two people have been known to break the physics, Conservative Overlord Darth George and his sidekick Right-wing Ricky. After using a moding cheat on an online game, Darth George was able to defeat the virtual Chuck Norris, which was before believed to be impossible. This resulted in the destruction of physics as it was formerly known, and created a New Physics, ruled by Darth George, and to a lesser extent, Right-wing Ricky.

[edit] Known Theories and Laws
The Theory You Know Is Outdated
This one is the main theory of physics, and all its foundations rest upon it. The inter-physicians relationships rest solely upon this theory alone.




Physics Act of 1603
Unified Law of Subsequent Albums
Quantum Monty Hall problem
String Theory
So That's What You Kids Call It These Days
Particulate Atheism Resonance Theory II
STL
Murphy's Law

Answer 4

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