Answer: B. A magnet pulls a nail towards it
Explanation: Out of the list of answers, this is the only answer where a force is acting on an object. the act of the magnet pulling on the nail is the force, and the nail is the object.
Weak winds that blow for short periods of time with a short fetch.
Answer:
x=1.25m
Explanation:
The <em>Center of mass </em>of the system is defined as the point where whole mass of the body is appeared to be concentrated.
The center of mass of the system is given by
x=
where m1 is mass of man =60 kg
m2 mass of board =20 kg
let the man be at the origin x1 =0 , x2 =5m
by substituting in above formula
x =
=
=1.25 m
x=1.25m
So the center of mass of the system is at 1.25 m from man.
Answer:
25.3J
Explanation:
Given parameters:
Mass of aluminum = 3.05g
Initial temperature = 10.8 °C
Final temperature = 20 °C
Specific heat = 0.9J/g °C
Unknown:
Amount of heat needed for the temperature to change = ?
Solution:
To solve this problem, we use the expression:
H = m C Ф
H is the amount of heat
m is the mass
C is the specific heat capacity
Ф is the change in temperature
H = 3.05 x 0.901 x (20 - 10.8) = 25.3J