Answer:
c. 60 m/s
Explanation:
As you can see in the graph, or the description of the graph, the change in speed since the acceleration at 20 seconds was 0 will be all the acceleration that we added up after that second, since we accelerated at 6 m/s until 30 seconds, that means that the object remained 10 seconds accelerating at 6m/s, so 10seconds times 6 m/s that is 60 m/s in the change in speed between the 20th second and the 30th second.
A wave with a greater amplitude carries more energy to wherever it goes.
Answer:Sound travel faster in warm room.
Explanation:The speed of sound depends on the temperature of the medium. Mathematically, the relation between the speed of the sound and the temperature is give by:v=
is the ratio of the specific heats
R is the gas constant
T is the temperature of the medium
We know that the temperature of the warm room is more as compared to the cold room.
So, it is clear that the sound travel faster in a warm room. The particles move faster when the temperature is high.
The electrostatic force between two charges Q1 and q is given by

where
ke is the Coulomb's constant
Q1 is the first charge
q is the second charge
r is the distance between the two charges
Re-arranging the formula, we have

and since we know the value of the force F, of the charge Q1 and the distance r between the two charges, we can calculate the value of q:

And since the force is attractive, the two charges must have opposite sign, so the charge q must have negative sign.