Answer:
A. At warm tempetures, molecules move around more.
Explanation:
I'm at k12 and I just took the test got it right. Physical Science: Unit 2 Test
Answer:Jack will run faster when he feels like it!
Explanation:
Answer:
His kinetic energy increases, potential energy decreases
The sum of kinetic and potential energy is a constant at any instant before he comes to rest.
Explanation:
Snowboarder is starting from a height and moving to the down direction. As he moves down his velocity increases, we know that kinetic energy is given by the expression 
, so as he moves his kinetic energy increases.
When the snowboarder is starting his potential energy is maximum(Potential energy = mgh), as he comes down his potential energy decreases.
Based on this we can conclude that the sum of potential energy and kinetic energy is a constant at any instant for a snowboarder before he comes to rest.
mgh+= Constant
Answer:
a. Concave mirror, radius of curvature = 16 cm b. magnification = 2
Explanation:
a. Since the image is upright and larger than the object, we need a concave mirror.
We know image height, h'/object height, h = -image distance, d'/object distance, d
h'/h = -d'/d
Using the real is positive convention,
h'= + 5.4 cm, h = + 2.7 cm and d = + 12 cm.
So, + 5.4 cm/+ 2.7 cm = -d'/+ 12 cm
2 = -d'/12
d' = -2 × 12 cm
= -24 cm
Using the mirror formula 1/d + 1/d' = 2/r where r = radius of curvature of the mirror
1/+12 + 1/- 24 = 2/r
1/12(1 - 1/2) = 2/r
1/12(1/2) = 2/r
1/24 = 2/r
r/2 = 24
r = 2 × 24
r = 48 cm
b.
magnification = image height, h'/object height,h = + 5.4 cm/+ 2.7 cm = 2
