To find the acceleration of an object, we use the definition of acceleration, which is the rate of change of velocity. This means we calculate the change in velocity and divide it by the time taken for that change.
Acceleration (\(a\)) is given by the formula:
\[ a = \frac{\text{Change in velocity}}{\text{Time taken}} = \frac{v - u}{t} \]Substitute the initial velocity, final velocity, and time into the acceleration formula:
\[ a = \frac{40 \text{ m/s} - 20 \text{ m/s}}{5 \text{ s}} \]The acceleration of the object is \(4 \text{ m/s}^2\).
Correct Option: A) 4 m/s²
To find the total distance traveled, we need to use the fundamental relationship between speed, distance, and time. The formula for distance is the product of speed and time.
The relationship between speed, distance, and time is given by:
\[ \text{Distance} = \text{Speed} \times \text{Time} \]Or, in symbols:
\[ D = S \times T \]D) 120 kilometers. The car travels 120 kilometers in 2 hours at a speed of 60 km/h.
To determine the type of motion when an object's speed remains constant, we need to understand the definitions of different types of motion, particularly focusing on how speed and velocity change over time.
Correct Option: B) Uniform motion
The concept of average speed is fundamental in physics and mathematics, especially in problems related to motion. It is defined as the total distance covered by an object divided by the total time taken to cover that distance. This question tests the basic understanding of this definition.
This formula accurately represents the definition of average speed.
D) Average speed = Total distance traveled / Total time taken. This is the correct and universally accepted formula for calculating average speed. It represents the ratio of the total path length covered to the total duration of the journey.
The question asks for the term that describes the change in an object's position over time. This requires understanding fundamental concepts in kinematics, specifically the definitions of displacement, distance, velocity, and acceleration.
Correct Option: D) Displacement is the change in an object's position. It is a vector quantity that describes both the magnitude (how far) and direction of the change from the initial to the final point. For example, if an object moves from point A to point B, its displacement is the straight-line vector from A to B.
The question asks to identify which of Newton's laws describes the tendency of an object to maintain its state of motion (rest or uniform motion) unless acted upon by an external force. This concept is fundamental to classical mechanics and is often referred to as the law of inertia.
Correct Option: A) Newton's First Law of Motion is also known as the Law of Inertia. It states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external, unbalanced force. This directly corresponds to the statement in the question.