A student pushes a box across a rough horizontal floor. If the amount of work done by the student on the box is 100 J and the am
1 answer:
Answer:
60J
Explanation:
friction is the opposition to the motion of an object. Before a body can be set in motion, part of the energy or work-done must be used to overcome friction.
While kinetic energy is the energy associated with a body due to its motion.
Since friction tends to oppose the motion of a body,when a body start to move, some of the energy applied to the body to cause its motion is converted to heat due to friction.
Hence if a work-done of 100J is applied to a body that requires 40J of the work to overcome friction, the total change in the kinetic energy can be expressed as
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a) , 1.6 A
b) , 1.33 A
Explanation:
a)
In this situation, we have two resistors connected in series.
The equivalent resistance of resistors in series is equal to the sum of the individual resistances, so in this circuit:
where
Therefore, the equivalent resistance is
Now we can use Ohm's Law to find the current flowing through the circuit:
where
V = 8 V is the voltage supplied by the battery
is the equivalent resistance of the circuit
Substituting,
The two resistors are connected in series, therefore the current flowing through each resistor is the same, 1.6 A.
b)
In this part, a third resistor is added in series to the circuit; so the new equivalent resistance of the circuit is
where:
Substituting, we find the equivalent resistance:
Now we can find the current through the circuit by using again Ohm's Law:
where
V = 8 V is the voltage supplied by the battery
is the equivalent resistance
Substituting,
And the three resistors are connected in series, therefore the current flowing through each resistor is the same, 1.33 A.
Answer:
increase.
Explanation:
According to the newton’s second law of motion force is expressed as product of mass and acceleration.
F = m a
If the force acting is constant, then.
m∝
That is if the mass of object increases the acceleration decreases and vice versa. The above equation is used when the force acting on the body is constant.
As the thrust force from the rocket engine is constant throughout there will be a variation in the mass or acceleration.
Thus, it won't stay the same.
As the weight of the car is maximum at the start because of the fuel present in the rocket engine and minimum at the end as the fuel burns throughout the journey of the car. Weight will be minimum at the end and hence acceleration is maximum at the end.
Thus, it won't decrease.
As the acceleration is going from minimum at the start to maximum at the end, therefore it is continuously increases throughout its journey.
Thus, it will increase.