Question

#4. A vase was placed on the coffee table. The coefficient of static friction between the vase and the table is 0.3689, whereas the coefficient of kinetic friction is 0.1339. The vase weighs 1.0707kg. A cat decided to redecorate the room by pushing the vase off the table. As the cat pushes the vase with its paw, the vase moves. Then, the cat maintains a constant applied force of 7.37N on the vase in the positive x-direction. What is the acceleration of the vase in the x-direction during the time when the vase is moving?

#6. A student has two springs. Spring 1 is twice the mass of spring 2. The student first puts spring 1 into a massless pouch and suspends it from spring 2. Spring extension was noted to be 12.69cm. Then, they put spring 2 into a massless pouch and suspend it from spring 1. Spring extension was noted to be 16.42cm.
What is the ratio of k1/k2?

Answer 1

Once the body or system starts its motion then only kinetic friction acts till the body continue its state of motion.

In this question it is saying to calculate acceleration of vase in the x-direction during the time when the vase is moving. Since cat applied force on the vase is in x-direction hence its acceleration will be also in the x-direction and since vase is moving hence kinetic friction will act on the body. Calculate the value of kinetic friction and then subtract it to force applied by cat as friction force always acts in the opposite durection of motion of body and then apply F net = m*a and calculate acceleration of the vase.