Simple Physics

Tommy B

Tommy B

Tommy B

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1. A car of mass 850 kg accelerates at 2 m/s2. What resultant force is accelerating it?

HOW THE **** do you work this out. Excuse me for being impatient but I've lost it. I don't understand how the hell you get the speed into N. You can use W=MG to get the 850kg into N, bu what about the friggin speed. I hate physics.

Cheers :D
 
1. A car of mass 850 kg accelerates at 2 m/s2. What resultant force is accelerating it?

OK. So I've got F=MA, 850*2 = 1700N
I've also got 850*9.8 = 8500N

So Square root of those two added togethor?
 
Because I need to work out the resultant force so both the forces need to be in N.

Please can someone confirm?
 
This always happens to me. I try and be too complicated. Why the hell do I have to make everything so complicated. Grrr.

Thanks to those who helped!
 
I've been doing Physics since about 7am. Is it possible my brain has just turned off.

Seriously I'm now stuck on part two.

Mass of car = 1.3x10^3 kg

b) When the accelerating car reaches a speed of 2.2ms-1, the total force opposing the motion of the car is 410N. Calculate the driving force provided by the wheels.
 
Arcade Fire said:
Same as before - you need to use F=ma. In this case on the 'F' side of the equation you have

D - 410 = ma

where D is the driving force of the engine.
Click to expand...

But 2.2ms-1 is the speed, not the acceleration.
 
Arcade Fire said:
I don't think that you can solve this without more information. For example, is the car still accelerating at a constant rate of 2m/s^2? Even then the question is made much trickier by the fact that you're now considering an opposing force, and the way that the question is worded makes it sound as though it's a variable force.

Can you type out the whole question? Visage, do you agree with me?
Click to expand...

With pleasure...

5) A car accelerates at a steady rate of 2.5ms-2 along a straight, level road. The mass of the car is 1.3X10^3 kg.

a) calculate the magnitude of the resultant force acting on the car?
F = MA = 1.3X10^3 * 2.5 = 3250N

b) When the accelerating car reaches a speed of 2.2ms-1, the total force opposing the motion of the car is 410N.

Calculate

1) The driving force provided by the wheels.
2) The power delivered to the wheels of the car.
 
Arcade Fire said:
Ah okay, that makes it much nicer. All you need to know for part (b) is that the resultant force is 3250 N, and that the force opposing the motion is 410 N. So if the driving force is D, then you just need to do

D - 410 = 3250
D = 3660

and for the next part, you use P=Fv, or Power = Force x Velocity, with a force of 3660 N and a velocity of 2.2 m/s.
Click to expand...

Cheers. If you want the quid email me your paypal addy :D
 
This mechanics paper is driving me insane. I found the quantum one a joke and apparently that's a lot more difficult than this. I've now been asked to explain the horizontal motion of a ball shows that air resitance is negligible. It then gives me a stupid graph with vertical and horizontal distance. How in the love of God can you state air resistance is negligible. I take it I just put that mavity pushes the ball down at exactly 9.81 ms-2
 
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