themster said:Homework Statement
Ascending a 1 in 10 hill, a 1500 kg car slows down from 100 km/h to 50 km/h in a distance of 400 m. Calculate the net tractive force F between the tyres and the road assuming F remains constant and wind resistance can be neglected. Is the driver braking during this period?
I am told the answer is 379N but have no idea how to go about it
any help would be greatly appreciated
themster said:would i convert the velocities into m/s?
Do I find the differences between the KE and compare that with the PE?
Would you be able to demonstrate it?
themster said:but how to you calculate gain in PE? PE1 - PE2?
I know PE = mgh but what would the value for h be?
I meant worked example by demonstrate it :)
themster said:ok sorry i didnot understand it first - i think i was confused by a 1 in 10 hill - what is it?
rude man said:k.e. after = k.e. before - gain in p.e. - friction energy loss.
k.e. = 1/2 m v2 in general
friction energy loss = friction force x distance covered
You are looking for the friction force.
Always use SI units or you'll get the wrong answer:
meter, kilogram, Newton, meters/second, g = 9.81 m/sec2 etc.
Don't know what you mean by "demonstrate it".
Net tractive force is the total amount of force applied to an object in a specific direction, taking into account all the forces acting on the object. In mechanics, it is often used to describe the force required to move an object, such as a vehicle, against resistance.
To calculate net tractive force, you must first identify all the forces acting on the object in question. Then, use the formula Fnet = ma, where Fnet is the net tractive force, m is the mass of the object, and a is the acceleration of the object in the direction of motion.
The main factors that affect net tractive force include the mass of the object, the force of gravity, the coefficient of friction between the object and its surface, and any additional external forces acting on the object, such as wind resistance or mechanical resistance.
Yes, net tractive force can be negative if the forces acting on the object are in opposite directions. This means that the object will experience a net force in the opposite direction, causing it to slow down or move in the opposite direction.
In real-world scenarios, net tractive force is used to understand the motion of objects, such as vehicles or machinery, and to determine the amount of force needed to overcome resistance and achieve a desired velocity. It is also used in engineering and design to ensure that vehicles and machines are able to function properly and efficiently.