After a spring is compressed 0.2 meters from its uncompressed length it exerts a 20 newton force on a 0.4 kg block resting on a horizontal frictionless surface. after it is released the block will reach a maximum velocity of a. 2.1 m/s
b. 3.2 m/s
c. 6.3 m/s
d. 10.0 m/s
e. 100 m/s
can someone walk me through this.
I know it's b but how do I show my work for it.​

Jackson is designing a new heater, and he wants to experiment with different thermally conductive materials. which of these materials would be useful in conducting heat?

A250-n box is at rest on a frictionless horizotal floor. then a person shoves the box with a non-zero force of magnitude p. which statement best describes the relationship betweeen p and the motion of the box after it was shoved? -the box will not move when p< 250n but otherwise will accelerate at a constant rate that is directly proportional to p - the box will begin moving at a speed that is directly proportional to p, then will gradually slow to a halt -the box will move with constant velocity at a speed that is directly proportional to p -box will accelerate across the floor at a constant rate that is directly proportional to p

Two conductors, a and b, are each in the shape of a tetrahedron. but of different sizes. they are charged in the following manner: 1. tetrahedron a is charged from an electrostatic generator to charge q. 2. tetrahedron a is briefly touched to tetrahedron b. 3. steps 1 and 2 are repeated until the charge on tetrahedron b reaches a maximum value. if the charge on tetrahedron b was q/4 after the first time it touched tetrahedron a. what is the final charge qbmax on tetrahedron b?