*sad*
I have to complete these questions by my next physics tutorial, due on the date when my physics prac report is due + I'm presenting a reading in an English unit + I have an actual physics exam the following week.
I don't know why I have such problems in solving mechanic questions, but I guess I'm just really lame...
Could anyone help me with these questions? I've even changed the values so I couldn't just copy down the help you guys provide, as I really do want to learn - I just would like to see how people would solve these equations. Maybe there is an easier way than the way I am trying to learn.
Sorry to dump this on you... if you have the time, please help I've included the formula I believe is supposed to be with each equation and what I've done, but I could be/am most likely wrong :/
- Jai
Questions
1) A wheel has a constant angular acceleration of 2.5 rad s-2. During a 3 second interval it turns through an angle of 140 radians. Assuming the wheel started from rest, how long had it been in motion at the start of the given time interval?
http://en.wikipedia.org/wiki/Angular_acceleration
w = 2.5
t = 3
theta = 140
u = 0
a = w/t = theta/t^2
= 2.5/3
= 0.833
I'm so confused...
2) A rear-wheel-drive car supports 40% of its weight on its two drive wheels and has a coefficient of static friction of 0.60 with a horizontal straight road. Find the vehicle's maximum acceleration.
http://en.wikipedia.org/wiki/Coefficien ... c_friction
u = 0.6
--> horizontal
a = ?
f = u Fn
Where does the 40% come in??? aaaarsh. Am I retarded?
3) An object attached to a spring executes simple harmonic motion with an amplitude of 20 cm. What percentage of its total energy is potential energy when it is 14 cm from the mean position?
http://en.wikipedia.org/wiki/Simple_harmonic_motion
Amplitude = 0.2m
x = .14m
F = -kx
....
4) A disk with a moment of inertia of 5 kg m2 rotates like a merry-go-round while undergoing a constant torque of 3 N m. At time t = 1 s, it's angular momentum is 2 kg m2 s-1. What is its angular momentum at t = 3.6 s?
http://en.wikipedia.org/wiki/Angular_momentum
I = 5
T = 3
t = 1, w = 2
t = 3.6, w = ?
L = I w
... ?
5) A 3 kg particle starts from rest at x = 0 and moves under the influence of a single force Fx = 5.8 + 4.3x - 3x^2, where Fx is in Newtons and x is in metres. Find the work done by the force as the particle moves from x = 1.7 to x = 3.6.
???
I'm sorry if I appear really idiotic. I really really just don't know what to do, and am too embarrassed to ask when everyone else seems to know what to do already. I know that's stupid, but yeah...
Thanks again, guys
Gender:
Points: 22732
Reviews: 377