A35-n bucket of water is lifted vertically 3.0m and then returned to its original position. how much work did gravity do on the bucket during this process? (a)180j (b) 90j (c) 45j (d) 0j (e) 900j

Work done, W = 0 J

Explanation:

It is given that,

Weight of the bucket, W = F = 35 N

It is lifted vertically 3 m and then returned to its original position. We need to find the work gravity do on the bucket during this process.

Work done when the bucket is lifted vertically, W₁ = -mgh

Work done when the bucket returned to its original position, W₂ = +mgh

Net work done, W = W₁ + W₂

W = 0 J

So, the work done on the bucket is zero. Hence, this is the required solution.

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