A box is being pulled across a horizontal surface by a 20 N force to the right. a. If the box moves at a constant velocity, what do you know about the forces acting on the object?
b. If the box moves at a constant velocity, how much force opposes the motion of the box?
c. If the box experiences a force of 15 N to the left, along with the 20 N force acting to the right, what is the net force on the box?

Im pretty sure it's C

Explanation:

The answer A talks about constant speed, which does not correspond to Net Force. The answer B, talks about constant velocity, but talks about how much force apposes the box. The answer C talks about the value of the net force acting on the box, so im pretty sure the answer is C.

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s