A mass 25kg is attached to a spring which is held stretched a distance 120 cm by a force F=300N (Fig. 7-28), and then released. The spring compresses, pulling the mass. Assuming there is no friction, determine the speed of the mass m when the spring returns: (a) to its normal length (x = 0). (b)find the spring constant k?

Explanation:

Spring is stretched by force f to distance

"X"

now here by force balance we can say

f = kx

k = !

now here we will we say that energy stored in the spring will convert into kinetic energy

kx² = mv²

(x² = mv²

now solving above equation we will have

PART 2)

now for half of the extension again we can use energy conservation

ka²-k(x/2)² = 1 {mv²

¾fx=mv²

now the speed is given as

3 fr 4m V=

the small 0.38-kg slider is known to move from position a to position b along the vertical-plane slot. determine (a) the work done on the body by its weight and (b) the work done on the body by the spring. the distance r = 0.70 m, the spring modulus k = 154 n/m, and the unstretched length of the spring is 0.53 m

explanation:

-reverse card

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it