]A net force of 15 N is applied to a cart with a mass of 2.1 kg. How long will it take the cart to travel 2.8 m, starting from rest? Acceleration=7.14m/s²

we will use one of the kinematic equations :

d = u*t+0.5*a*t²

in which : d : distance

u : initial velocity

a : acceleration

t : time

after substitution :

initial velocity = 0 m/s (from rest)

2.8 = 0*t+0.5*7.14*t²

2.8 = 3.57*t²

t² = 0.7843

after square root

t = 0.885615 s

I hope this answer will help

5 w for 1hr = 5x60x60 joules=300x60=3000x6=18,000j as total energy conversion. efficiency of bulb needed for radiant to thermal within 18000