You carry a 7.0 kg bag of groceries 1.2 m above the ground at constant velocity across a 6.8 m room. how much work do you do on the bag in the process? a) 396j b) 466j c) 0.0j d) 82j

Option (d)

Explanation:

m = 7 kg

h = 1.2 m

d = 6.8 m

Work done in lifting the bag = F x h x Cos 0 = mg x h x 1 = 7 x 9.8 x 1.2

                                               = 82.32 J

Work done in moving the bag = f x d x Cos 90 = 0

So, teh work done in complete process = 82.32 + 0 = 82.32 = 82 j

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