______ creates heat in earths interior when dense substance sink into earths core.
1 answer:
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Initially they are connected in parallel, so they have the same voltage V=120 V at their ends. Therefore we can use Ohm's law to calculate the resistance of each appliance:
When they are connected in series, they are crossed by the same current I. The equivalent resistance of the circuit in this case is
, so we can use Ohm's law for the entire circuit to find the current in the circuit:
When they are connected in series, they are crossed by the same current I. The equivalent resistance of the circuit in this case is
Answer:
1) Option b. The acceleration is positive when it is thrown up and negative when it is thrown down.
2) Option d. Both B & C
Explanation:
Question 1)
Acceleration is defined as the rate of change of velocity with respect to time.
When an object is thrown up, its velocity is maximum at the initial point and decreases as the object moves up. Since, the velocity is decreasing, the acceleration will be negative. This can also be proven from the formula mentioned above. When the object is thrown up, initial velocity(vi) is maximum and the final velocity (v_f) is zero, as the object rests for a very tiny moment at its maximum point. This will give a negative numerator and hence the value of acceleration will be negative.
When an object is thrown down, its velocity is zero at the start of the motion and increases as the object falls down. Since, the velocity is increasing in this case, the acceleration will be positive.
Therefore, Option b, gives the correct answer.
Question 2)
When an object falls freely, it falls under the action of gravity under a constant acceleration known as gravitation acceleration. Gravitational acceleration is represented by g and is equal to 9.8 m/s².
Since, the textbook is falling freely, its acceleration will be constant i.e. equal to gravitational acceleration.
When the object falls down, with every second its velocity increases. The velocity in minimum(zero) at the start and is maximum just before the object hits the ground.
So, when the textbook is dropped, it will fall with constant acceleration and its velocity will be increasing.
Therefore, for this question, Both B and C are correct.