Aramp is often used to raise an object. if 80 joules of energy are needed to lift an object to a platform but 100 joules are used in rolling the object up the ramp, what percent of energy was wastec in the form of heat due to friction?

20 % of energy is wasted

Explanation:

If 100 joules of energy are used when 80 joules was needed, then 100 - 80 = 20 joules were wasted. Given that 100 joules are proportional to 100 % of energy used, then 20 joules is proportional to x %, therefore:

20 J/100 J = x%/100%

x = 20%

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