በተደጋጋሚ ስለምወጡ ሥሯቸው |freshman course | physics | chapter 1| Common mid exam questions

Join us on telegram
@esku2017
In this video we discuss
1. A vector is a quantity that is completely specified by only a number and unit.
False
Explanation:
A vector is a quantity that is characterized by both magnitude and direction.
2. Multiplying a vector quantity by a scalar results in a new vector quantity with altered magnitude but the same direction.
True
✅ When a vector is multiplied by a scalar, its magnitude changes according to the scalar value, but its direction remains unchanged.
3. Electric current is a vector quantity.
False
Explanation:
Electric current is a scalar quantity. ⚡
4. What is the unit vector in the direction of vector A = 2i + 2j - k?
A .(1/3)i + (2/3)j - (2/3)k
B i + 2j - 2k
C i + j + k
D (2/3)i + (2/3)j - (1/3)k
Explanation:
To find the unit vector in the direction of vector A, we first calculate its magnitude: |A| = √((2)^2 + (2)^2 + (-1)^2) = √(4 + 4 + 1) = √9 = 3.
Next, we divide each component of vector A by its magnitude: Unit vector = (1/|A|) * A = (1/3) * (2i + 2j - k) = (2/3)i + (2/3)j - (1/3)k. ⚖️
Thus, the correct answer is D.
5. If the dimensions of a rectangle are 3.2m by 5.55m, the area of the rectangle to the appropriate significant digits is equal to:
A.17.76
B.17.8
C.17.7
D.18
Explanation:
✅ The area of a rectangle is calculated by multiplying the length and width.
In this case: Area = 3.2 m × 5.55 m = 17.76 m².
based on the rules for significant digits, when multiplying, the result should have the same number of significant digits as the factor with the least number of significant digits
, . 3.2 has two significant digits
Thus, the correct answer is 18 m².
6. Which one of the following alternatives contains only fundamental physical quantities?
A.force, velocity, displacement, momentum,
B. work, displacement and distance
C.force, mass, and velocity
D.time, temperature, and current
💡 Explanation:
Fundamental physical quantities are those that cannot be derived from other physical quantities.
Therefore ,the answer is D
7. Which one of the following experimental errors can be reduced by taking repeated measurements?
A.Zeros errors
B.Parallax errors
C.Systematic errors
D.Random errors
💡 Explanation:
✅ Random errors in measurements can be reduced by taking repeated measurements to minimize their impact on accuracy. 📉
Therefore ,answer is D
8. Which number below does NOT have three significant figures?
A 0.0307
B 0.0370
C 37.0
D 0.00037
💡 Explanation:
✅ Significant figures are the digits in a number that carry meaningful information about its precision.
Therefore, the correct answer is D. 0.00037.
9. The change in position of an object is called
A.Distance
B.Speed
C.Velocity
D.displacement
💡 Explanation:
✅ Displacement refers to the change in position of an object. 🛣️
💡 It is a vector quantity, meaning it has both magnitude and direction, and it represents the shortest path between the initial and final positions of the object. 📏
💡 Distance is the total path length traveled by an object, regardless of direction. 🌍
💡 Speed is the rate at which an object covers distance, and it is a scalar quantity. ⏱️
💡 Velocity is the rate of change of displacement, and it is a vector quantity. 📈
Answer D
10. What happens to a vector if its magnitude changes but its direction remains the same?
A.It becomes a scalar.
B.It becomes a zero vector.
C.It remains the same vector.
D.It becomes a different vector.
Answer D