Answer:
Conduction, radiation and convection all play a role in moving heat between Earth's surface and the atmosphere. Since air is a poor conductor, most energy transfer by conduction occurs right near Earth's surface
When iron is exposed to moisture and oxygen it starts to rust.
Answer:
A) Must be done 19806.62 joules of work.
B) The average power is 1320.44 Watts.
Explanation:
A) First, we're going to use the work-energy theorem that states total work (
) done on an object is equal to the change in its kinetic energy (
):
(1)
So, all we must do is to find the change on kinetic energy. Because we're working with rotational body, we should use the equation 
for the kinetic energy so:
(2)
with 
the initial angular velocity, 
the final angular velocity (is zero because the wheel stops) and I the moment of inertia that for a thin hoop is 
, using those on (2)
(3)
By (3) on (1):
B) Average power is work done divided by the time interval:
NOTE: We use the relation 
to convert 280 rev/min(rpm) to 29.32 rad/s
Answer:
(a) Girl acceleration = 0.15 m/s², (b) Sled acceleration = 0.93 m/s²
Explanation:
Given:
M1=Mass of girl = 43 Kg
M2= mass of Sled = 7.1 Kg
Force F= 6.6 N
To Find (a) a1 = girl acceleration (b) a2 = sled acceleration
Solution:
F1 = F2 = F (Newton's 3rd Law)
F=ma (Newton's 2nd Law)
(a) F = M1a1
⇒a1 = F/M1 = 6.6 N / 43 Kg = 0.15 m/s²
(b) a2 = F / M2 = 6.6 N / 7.1 Kg = 0.93 m/s²
