Check all the boxes that correspond to forces doing zero work gravity acting on a projectile that has been launched straight up
You pushing your stalled car, but it doesn't budge
Drag acting on a plane flying horizontally
gravity acting on your car as it drives horizontally
An olympic weightlifter holding a barbell above their head (the barbell is motionless)
sliding friciton acting on a car slilding to a stop

The definition of work is force acting thru a distance: W = F * S

Forces doing zero work:

1) Pushing a stalled car that doesn't move

2) No work is done by gravity on car driving horizontally

3) No work is done on a motionless barbell

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