what is the period of a wave that travels through a spring at 2.5 m/s and has a wavelength of 1.3 meters

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?

Using the free-body diagram, calculate the net force acting on the sled. is the sled in a state of dynamic equilibrium?

Suppose astronomers built a 140-meter telescope. how much greater would its light-collecting area be than that of the 10-meter keck telescope? express your answer using two sign