At t=0, a constant force of 10 N is applied to a body of mass 5 kg starting at rest in outer space where there are no other forces. What is the power (in Watts) that the force delivers at t = 2 s?

20 W.

Explanation:

Power is defined as the time rate oc change at which work is done.

Mathematically,

Power, P = workdone/time

Given:

vi = 0 m/s

F = 10 N

m = 5 kg

t = 2 s

F = ma

a = 10/5

= 2 m/s^2

Using equation of motion,

vf = vi + at

vf = 2 * 2

= 4 m/s

Workdone = potential energy, PE+ kinetic energy, KE

PE = 0

KE = 1/2 * m * v^2

= 1/2 * 5 * (4^2)

= 40 J

Power, P = 40/2

= 20 W.

radiation

explanation:

heat is transmitted by radiation

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)