Explanation:
q = mCΔT
where q is heat,
m is mass,
C is specific heat capacity,
and ΔT is temperature change.
For the first ball:
2500 J = (100 g) C (90°C − 25°C)
C = 0.385 J/g/°C
For the second ball:
5000 J = (200 g) C (90°C − 25°C)
C = 0.385 J/g/°C
The two metals have the same specific heat, and are likely the same metal (possibly copper or zinc).
Answer:
43.2 N
Explanation:
= Wavelength = 0.75 m
f = Frequency = 40 Hz
m = Mass of string = 0.12 kg
L = Length of string = 2.5 m
= Linear density = 
Velocity of wave is given by

The tension in string is given by

The tension in the string is 43.2 N
Note that this is a position vs time graph.
From A to B, the graph is a straight line with a nonzero slope. This indicates a constant velocity.
From B to C, the graph is a straight line with 0 slope. This indicates a constant position, i.e. the object remains stationary.
From C to D, the graph is a straight line with a nonzero slope. This indicates a constant velocity.
A) law of inertia. an object in motion stays in motion