Answer:
when the ball is at its highest in the air.
Explanation:
I don't know for sure, but when the ball is in the air it has potential energy to fall(or something like that).
Answer:
36N
Explanation:
First draw a diagram so you can see which forces act in which direction.
Then define which is your positive direction. I chose the direction of accelleration (downward) to be positive. This means that the weight of the object is also acting in the positive direction but Tension is acting in the negative direction.
If the elevator which contains the object within is accellerating at 2.6 ms^-2 then the object and string system is also accellerating at the same rate.
F = ma where F is the resultant force.
Resultant for is Weight + Tension but tension is in the negative direction so
F = mg -T
F = 5g - T
F = ma so F = 5 x 2.6
13 = 5g-T
T = 5g - 13
T = 36N
(I've taken g = 9.8ms^-2 but if this is for a physics class I'd take it to be 9.81ms^-2)
Explanation:
The total energy of the system remains conserved. It just converts from one form of energy to another.
The battery of the cell phone contains chemicals. As the electricity is passed through the cell phone, the electrical energy is converted to chemical energy. As she notices that the phone is warm and after the battery has been fully charged and the student unplugs her cell phone, the phone vibrates when a message arrives, this shows the conversion of chemical energy to mechanical energy, thermal energy etc.
Hence, we can say that the correct option is (b).