Motion Class 9 MCQ Online Test

The acceleration of a body moving with uniform velocity is always zero. This is because acceleration is the rate of change of velocity, and if the velocity is constant (uniform), there is no change in velocity over time, resulting in zero acceleration.

The statement is true. The odometer is a device in an automobile that measures the total distance traveled by the vehicle. It is typically located on the dashboard and is used to provide the driver with information about the distance covered during a trip or the total distance accumulated over the lifetime of the vehicle. This information is important for various purposes, such as maintenance scheduling, fuel efficiency calculations, and resale value estimation.

Acceleration is a vector quantity because it has both magnitude and direction. In physics, acceleration is defined as the rate of change of velocity, and velocity is a vector quantity as it includes both speed (magnitude) and direction. Therefore, since acceleration is directly related to velocity, it also possesses both magnitude and direction, making it a vector quantity.

When a particle moves in a circular path of radius "r," the displacement after half a circle is equal to the diameter of the circle i.e. 2r. In other words, the particle ends up exactly opposite to its starting point after traveling half the circumference of the circle, resulting in a displacement of twice the radius.

The average speed is calculated by dividing the total distance that something has traveled by the total amount of time it took it to travel that distance. This measure gives an overall indication of how fast an object is moving, taking into account both the distance covered and the time taken. It is different from velocity, which also considers the direction of motion, and displacement, which measures the change in position from the starting point to the ending point. Speed, on the other hand, is a general term that refers to how fast an object is moving without considering the distance or time taken.

The boat starts from rest and accelerates at a constant rate of 3.0 m/s^2 for 8.0 seconds. To find the distance traveled, we can use the equation d = v0t + (1/2)at^2, where d is the distance, v0 is the initial velocity (0 m/s), t is the time (8.0 s), and a is the acceleration (3.0 m/s^2). Plugging in the values, we get d = 0(8.0) + (1/2)(3.0)(8.0)^2 = 0 + 12(64) = 768 m. Therefore, the boat travels a distance of 768 m. However, since the boat starts from rest, we only consider the distance traveled during the given time of 8.0 seconds, which is 96 m.

The treads on the soles of shoes are designed to increase friction between the shoe and the ground. This helps to prevent slipping and provides better traction, especially on wet or uneven surfaces. The other options are incorrect because they do not accurately reflect the purpose of shoe treads.

The numerical ratio of displacement to distance for a moving object can be equal to 1 or less than 1 because displacement is the shortest distance between the initial and final position of an object, while distance is the total path length traveled by the object. In some cases, the object may move in a straight line from the initial position to the final position, resulting in the displacement being equal to the distance. However, if the object follows a curved path or changes direction, the displacement will be less than the distance. Therefore, the ratio can be equal to 1 or less than 1.

The given v-t graph shows a horizontal line indicating a constant velocity over time. This implies that the object is moving with a uniform (constant) velocity, meaning it is in uniform motion. If the object were at rest, the line would be at zero velocity. Increasing acceleration would be shown by a sloping line (increasing velocity), and non-uniform motion would result in a curved line.

The speed of an object in circular motion can be calculated using the formula v = 2πr/T, where v is the speed, r is the radius of the orbit, and T is the time taken to complete one revolution. In this case, the radius of the orbit is given as 42,250 km and the time taken to revolve around the earth is given as 24 hours. Converting the radius to meters (42,250 km = 42,250,000 m) and the time to seconds (24 hours = 24 x 60 x 60 = 86,400 s), we can plug these values into the formula to find the speed. v = 2 x 3.14 x 42,250,000 / 86,400 = 3074 m/s. Therefore, the correct answer is 3074 m/s.