Spring constant and maximum acceleration

In summary, the spring constant k for a spring designed to bring a 1150 kg car to rest from a speed of 99 km/h, with the occupants undergoing a maximum acceleration of 5.0 g, can be calculated by converting the initial velocity to m/s, calculating the acceleration, determining the distance over which the car will stop, and using the formula F = -kx to find the spring constant. Using this method, the spring constant is calculated to be 7318.1 N/m.
  • #1
cgward
5
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What should be the spring constant k of a spring designed to bring a 1150 kg car to rest from a speed of 99 km/h so that the occupants undergo a maximum acceleration of 5.0 g?


I am unsure of the formula to find the spring constant by determining a maximum acceleration of 5 g
 
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  • #2
What have you tried so far? Can you think of any formulas that might be relevant?
 
  • #3
PE= 1/2 k x^2
 
  • #4
cgward said:
What should be the spring constant k of a spring designed to bring a 1150 kg car to rest from a speed of 99 km/h so that the occupants undergo a maximum acceleration of 5.0 g?


I am unsure of the formula to find the spring constant by determining a maximum acceleration of 5 g

This is how you should do it:

1- change the initial velocity to m/s
2- calculate acceleration: 5*9.8m/s^2 = -49m/s^2: note acceleration is negative to stop the car.
3- calculate the distance (x) over which the car come to halt: V^2= V^2 (initial)+2ax (V= final velocity = 0, x= distance, a=acceleration)
4- now you have 'x', calculate 'k' like this: F=-kx and F=ma (where m=mass)

Solution: m=1150kg, V(initial)=99km/h*(1000m/km)*(h/3600s)= 27.5m/s, V(final)=0, now:

0 = (27.5)^2 + 2*(-49)* x, x= 7.7m

now we can calculate 'k': ma = -kx (this come from F = -kx hook's law), so

1150kg*-49m/s^2 = -k * 7.7m, k = 7318.1 N/m

Note: I did this calculation quickly and I might have errors but the method should be all right.

Good luck!
 

FAQ: Spring constant and maximum acceleration

What is a spring constant?

A spring constant, also known as spring stiffness, is a measure of the resistance of a spring to being compressed or stretched. It is typically represented by the letter 'k' and has units of force per unit length (N/m or lbs/in).

How is the spring constant related to maximum acceleration?

The spring constant is directly related to maximum acceleration through Hooke's Law, which states that the force exerted by a spring is proportional to its displacement from equilibrium. This means that a higher spring constant will result in a greater force and therefore a greater maximum acceleration.

Can the spring constant change?

Yes, the spring constant can change depending on factors such as the material, shape, and size of the spring, as well as the temperature and applied external forces. However, for a specific spring, the spring constant remains constant as long as these factors remain the same.

How is the spring constant measured?

The spring constant can be measured using a variety of methods, such as a force gauge or a load cell, which measure the force required to compress or stretch a spring a certain distance. The inverse of this force divided by the distance is equal to the spring constant.

How does the maximum acceleration affect the spring's behavior?

The maximum acceleration affects the spring's behavior by determining the amplitude and frequency of its oscillations. A higher maximum acceleration will result in a greater amplitude and higher frequency of oscillations, while a lower maximum acceleration will result in smaller amplitude and lower frequency oscillations.

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