Efficiency is calculated through dividing the actual mechanical advantage by the hypothetical mechanical advantage:
- the actual mechanical advantage is 9J because that's how much work the light bulb doing
- the hypo. mechanical advantage is 100J. Ideally, in a perfect world, the light bulb can convert 100J input into 100J output, but do to resistance and other factors it is not possible.

change the decimal to a percentage:

the light bulb had 9% efficiency
Answers:
a) 
b) 
Explanation:
a) The centripetal acceleration
of an object moving in a uniform circular motion is given by the following equation:
Where:
is the angular velocity of the ball
is the radius of the circular motion, which is equal to the length of the string
Then:
This is the centripetal acceleration of the ball
b) On the other hand, in this circular motion there is a force (centripetal force
) that is directed towards the center and is equal to the tension (
) in the string:

Where
is the mass of the ball
Hence:

This is the tension in the string
Answer:
Explanation:
spring constant k = 425 N/m
a ) At the point of equilibrium
restoring force = frictional force
= kx = 10 N
425 x = 10
x = 2.35 cm
b )
Work done by frictional force
= -10 x 2.35 x 10⁻² x 2 J ( Distance is twice of 2.35 cm )
= - 0.47 J
= Kinetic energy remaining with the cookie as it slides back through the position where the spring is unstretched .
= 425 - 0.47
= 424.53 J
=