Answer : The correct option is, (b) Thermometer B, because it measures temperature more accurately than A.
Explanation :
Accuracy : It is defined as the closeness of a measured value to a standard or known value.
For Example: If the mass of a substance is 50 kg and one person weighed 48 kg and another person weighed 55 kg. Then, the weight measured by first person is more accurate.
Precision : It is defined as the closeness of two or more measurements to each other.
For Example: If you weigh a given substance five times and you get 1.8 kg each time. Then the measurement is said to be precise.
Level of precision is determined by the maximum number of decimal places.
As per question, the thermometer B has markings 40°, 45° and 50° at equal intervals and there are four small markings equally spaced in between the numbers and thermometer B has markings 40°, 45° and 50° at equal intervals but there is no small markings equally spaced in between the numbers. That means, thermometer B is measures temperature more accurately than thermometer A.
Hence, correct option is, (b) Thermometer B, because it measures temperature more accurately than A.
Answer:
8000J
Explanation:
The kinetic energy of the car lost during breaking are converted to thermal energy and are gained by the brakes.
Kinetic energy loss by car = thermal energy gained by brakes.
∆K.E = ∆T.E ....1
The Kinetic energy loss by car can be expressed as;
∆K.E = K.E1 - K.E2
Initial K.E = K.E1 = 10000J
Final K.E = K.E2 = 2000J
∆K.E= 10000J - 2000J = 8000J
From equation 1,
∆K.E = ∆T.E
∆T.E = 8,000J
thermal energy gain by brakes = 8,000J
<h2>The option ( c ) is correct </h2>
Explanation:
As the frequency of oscillation of any oscillator is doubled
The velocity of sound v = νλ
here ν is the frequency and λ is the wavelength
Now if ν becomes double , the wavelength λ becomes one half . The velocity of sound remains the same in the same medium .
Thus option ( c ) is correct
Explanation :
There are two types of collision i.e. elastic and elastic collision.
- Elastic collision : In this type of collision, the total momentum and the kinetic energy of the particles remains constant.
- Inelastic collision : In this type of collision, only the momentum remains constant while there is some loss of kinetic energy occurs.
From Newton's second law,
F = m a
a is the rate of change of velocity.
There is a inverse relation between the force and the time of collision.
The change in <em><u>momentum</u></em> will remain the same during a collision, the force needed to bring an object to a stop can be <em><u>increased</u></em> if the time of the collision is <u><em>decreased</em></u>.
