When lisa placed a balloon to her ear, she was able to hear what her sister was whispering from the other side of the room. when she removed the balloon, she was no longer able to hear what her sister was saying. what is the best explanation for what lisa discovered?
a) the material from which the balloon is made makes sounds seem louder.
b) there is no air pressure inside the balloon, which makes sound waves travel more quickly.
c) the air in the balloon is not as dense as the air outside the balloon, which makes sound waves echo.
d) sound does not travel around the air outside of the balloon as well as it does through the denser air pressure inside the balloon.

unbalanced force

explanation:

dec 23, 2016 - a load of bricks weighing 680 n a distance of 10 m across a parking lot. if if the worker pushes the cart with a constant force of 209 n, what work= force x distance = 220 n x 10 m = 2200 n.m = 2200 j i don't know where the person got it from, but the initial part, work= force x distance me.

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