Mechanics AS-level

[Syed.Mazahir.Rizvi]

Help guys any gud way to understand this subject within 3days....i mess up in imagination portion! any quick revision stuff.

 

[1992]

Help guys any gud way to understand this subject within 3days....i mess up in imagination portion! any quick revision stuff.

do u do phisycs??? its nearly the same but just using formulas!!
do some pastpapers and see how it goes

 

[Syed.Mazahir.Rizvi]

yup i do phyics...but dunno why i got messed up in mechnics...i;ve gone through the papers...done 5 so far gona do rest soon...i just want to know some topic wise revision which i can do....any tid bits..!!

 

[Zohaib Sherazi]

Do more pastpapers. At this stage that is the best remedy. Understand them, visualize the situation. 5 papers is too less. Do 10 more.

 

[Zazzyo]

Guys i came across this problem which i cannot answer.. im really rubbish in power and workdone questions :l ... anyhow this question is from the p1 bookby douglas quadling.. i cant even do one part of it.. plz help me out with this.. heres the ques,

6 ) The power developed by a car’s engine is top gear is 40 kW. When travelling at v ms-1 the car experiences air resistance of 0.32v^2 Newton’s. Neglecting other air resistances,

(a) Calculate the top speed of the car

(b) If the car has mass 1600 kg, calculate the acceleration of which it is capable when travelling at 40 ms-1

When climbing a hill the driver finds that with the engine at full power the car will not go 30ms-1.

(c) Find the angle the road makes to the horizontal.

 

[MAVtKnmJ]

6 ) The power developed by a car’s engine is top gear is 40 kW. When travelling at v ms-1 the car experiences air resistance of 0.32v^2 Newton’s. Neglecting other air resistances

What?
Plus it's only decent that you don't hijack other's threads, and start your own.

 

[Nera]

6 ) The power developed by a car’s engine is top gear is 40 kW. When travelling at v ms-1 the car experiences air resistance of 0.32v^2 Newton’s. Neglecting other air resistances,

I think if I am not mistaken that this is Q6 in Revision Exercise 2. Well the method tht I followed is quite long.

a) Top speed is achieved when acceleration is zero
Power = 40KW = 40,000 W Resistance is given as 0.32v^2
F=ma
F-0.32v^2 =0
So we say that F= 0.32v^2
Power = Force x Speed
40,000 = (0.32v^2) x (v)
V= 50m/s

b) We are given tht mass = 1600kg and speed = 40m/s. Power remains the same as it is the same engine. We have to first find the force
Power = Force x Speed
40,000 = (X) x 40
X= 1000N
Then use F=ma however don’t 4get 2 consider the resistive force.
F=ma ( Note that F is the resultant force)
1000- (0.32 (40^2)) = 1600a
a= 0.305 m/s^2

c) Again here use Power = Force x Speed
40,000 = (Y) x 30
Y=1333.33N
Now we can get the acceleration F=ma
1333.33-(0.32 (30^2)) = 1600a
a= 0.65333m/s^2

Find the Kinetic energy = 0.5 mv^2
= 0.5 x 1600 x (30^2)
= 720,000J
The Kinetic energy will be equal to the gravitational potential energy
gravitational potential energy = mgh
720,000 = 10 X 1600X h
h= 45m
Now we will use the acceleration a= 0.65333m/s^2 to find the actual distance
u = 0m/s v= 30m/s a= 0.65333m/s^2

v^2 = u^2 + 2as
30^2 = 0 + 2x 0.65333 x s
s= 688.7
sin α = S ( opposite side) ÷ h
Sin α = 45/ 688.7 α = 3.75


Hope that this helps and Best of Luck 4 ur exam !

 

[Zazzyo]

6 ) The power developed by a car’s engine is top gear is 40 kW. When travelling at v ms-1 the car experiences air resistance of 0.32v^2 Newton’s. Neglecting other air resistances

What?
Plus it's only decent that you don't hijack other's threads, and start your own.

Sory dude.. but i thought instead of wasting another thread y not post in here btw it says ' M1 help' ..

anywaiz thanks nera.. u can now start discussing ur own issue :S

 

[zahraahmed]

http://notezone.net/cambridgechem/chemi ... sis%5D.pdf can sum1 go in dix page 11 n do solve n gimme answers plzzzz i cant able to slove it n it might cum for exam help mee!!!!