The resistance indicated by the platinum thermometer at 200°C is 1.648 times the reference resistance Ro at 0°C.
The given equation is RT = Ro(1+AT+BT²), where A = 3.8×10⁻³°C⁻¹ and B = -5.6×10⁻⁷°C⁻². To determine the temperature that would be indicated on a platinum thermometer when the gas scale reads 200°C, we will have to use the given formula. RT = Ro(1+AT+BT²) .....(i)We know that the gas scale reads 200°C. Therefore, we can substitute T = 200°C in equation (i).RT = Ro (1 + A × 200 + B × 200²) = Ro (1 + 0.76 - 0.112) = Ro (1.648)Thus, the resistance that the platinum thermometer would indicate is 1.648 times the reference resistance Ro at 0°C. This is the solution to the problem.In summary, The given equation is RT = Ro(1+AT+BT²), where A = 3.8×10⁻³°C⁻¹ and B = -5.6×10⁻⁷°C⁻². To determine the temperature that would be indicated on a platinum thermometer when the gas scale reads 200°C, we substituted T = 200°C in equation (i) to get RT = Ro (1 + A × 200 + B × 200²) = Ro (1 + 0.76 - 0.112) = Ro (1.648).For more questions on thermometer
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4 Starting from rest on a level road a girl can reach a speed of 5 m/s in 10s on her bicycle. a Find the acceleration b Find the average speed during the 10s. c Find the distance she travels in 10 s. [2] Eventually, even though she still pedals as fast as she can, she stops accelerating and her speed reaches a maximum value. Explain in terms of the forces acting why this happens.
a. To find the acceleration, we can use the equation:
acceleration = change in velocity / time taken
Here, the initial velocity is 0 m/s (since she starts from rest), the final velocity is 5 m/s, and the time taken is 10 s. Therefore:
acceleration = (5 m/s - 0 m/s) / 10 s = 0.5 m/s^2
So the acceleration of the girl on her bicycle is 0.5 m/s^2.
b. The average speed during the 10 s can be found by dividing the total distance traveled by the time taken. We don't know the distance traveled yet, so we can use another equation:
distance = (initial velocity x time taken) + (0.5 x acceleration x time taken^2)
Here, the initial velocity is 0 m/s, and the time taken is 10 s. We already calculated the acceleration in part (a) as 0.5 m/s^2. Plugging these values in, we get:
distance = (0 m/s x 10 s) + (0.5 x 0.5 m/s^2 x (10 s)^2) = 25 meters
So the girl traveled 25 meters in 10 seconds.
c. As the girl pedals, she applies force to the pedals, which in turn transfers the force to the rear wheel. This force drives the bicycle forward, causing it to gain speed. However, when the bicycle picks up speed, air resistance (also called drag) comes into play, which increases. Eventually, the force of air resistance becomes equal and opposite to the force that propels the bicycle forward. This means that the net force on the bicycle becomes zero, stopping its acceleration and reaching its maximum speed, known as the terminal velocity. Even if the girl pedals faster, she won't be able to increase her speed because the drag force counteracts the propelling force.
Which statement describes the law of conservation of energy?
A. Energy cannot change forms.
B. Energy cannot be created or destroyed.
C. Air resistance has no effect on the energy of a system.
D. The total energy in a system can only increase.
Answer:
The correct answer is B. Energy cannot be created or destroyed.
The law of conservation of energy states that energy cannot be created or destroyed, but it can be transformed from one form to another. This means that in any physical process, the total amount of energy in a system remains constant. Energy can be converted from one form to another, such as from kinetic energy to potential energy or from electrical energy to light energy, but the total amount of energy in the system remains the same.
Option A is incorrect because energy can change forms, as mentioned above.Option C is incorrect because air resistance is a type of force that opposes the motion of an object, and therefore, it can cause a decrease in the kinetic energy of a system.Option D is incorrect because the law of conservation of energy states that the total energy in a system remains constant, it cannot increase or decrease without an external force acting on it.