1. Three identical 6.4kg masses are hung by three identical springs. Each spring has a force constant of 7.8 Kn/m and is 12cm long before any masses are attached to it. how long is the bottom most spring going to be after the three masses are hung on it a. 14.3 b. 16.2 c.12.8 d.10.7
2. a spring balance used to weigh candy is built with a spring the spring stretches 3.00 cm when a 15 n weight is placed in the pan. when the weight is replaced with 3 kg of candy, what distance will the spring stretch?
a.7.0 b.4.5 c.3.8 d.5.9
3. Spring A has a spring constant of 5 N/m and spring B has a force constant of 9 N/m. A weight of 2 kg is applied to spring A and a weight of 10 kg is applied to spring B. Which of the following is true for the final displacements of springs A and B?
a) Spring B has a larger displacement than spring A. b) Spring A has a larger displacement than spring B. c) Spring A and spring B have the same displacement.
4. a spring with a length of 25 cm is stretched to 28cm when a force of 12n was applied. what would the length be if the force is doubled
a.31 cm b.35 c.50 d. 45

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.