HOTS Questions: Motion for Class 9 - Free MCQ Test with solutions

 π radian is equal to 180 ° . Radian is a unit of measurement for angles, just like degrees are, and π is just the no. of radians that makes up that angle.

Uniform circular motion is always accelerated because the direction of velocity is continuously changing hence velocity is changing which causes change in acceleration. Hence the given statement is true. 
There are 3 equations of motion, 

• v = u+ at
• s = ut + 1 /2 at² 
• v² = u² + 2as

As, we can see there , we don't have the time in the third equation of motion.

Uniform circular motion is accelerated because the velocity changes due to continuous change in the direction of motion. So, even when the body moves ta a constant speed, its velocity is not constant. Thus, for a body moving in a circular path at a constant speed, its velocity changes continuously. The change in velocity gives rise to an acceleration in the moving body. Therefore circular motion is an acceleration motion even when the speed remains constant.

When the velocity decreases with respect to time it is termed as retardation or deceleration. In reality negative acceleration is commonly called retardation. Its SI unit. is m/s².

In physics, a body is considered to be at rest if its position does not change with respect to a particular frame of reference or observer over time. This means that the body remains stationary relative to the observer, indicating no change in position as time progresses.

Let the distance between A and B be D and time taken to cover the distance be T1 and T2.

Speed = Distance/Time

40 = (D/T1) and 50 = (D/T2)

T1 = (D/40)

also, T2 = (D/50)

Total time (T) = T1 + T2

⇒ (D/40) + (D/50) = (9D/200)

Total Distance = (D + D) = 2D

Average speed = Total Distance/Total Time Taken

= (2D/(9D/200)) = 400/9 = 44.4 km/hr

When a body moves with constant speed its acceleration is zero . The body is said to be accelerating if it moves in a uniform circular motion. The slope of the velocity- time graph gives Instantaneous acceleration . All the given statements are correct. Therefore ,  option ( d) is correct answer.

• Scalar - (D) Magnitude
  A scalar quantity only has magnitude and no direction. Examples include mass, temperature, and speed.

• Vector - (A) Magnitude and direction
  A vector quantity has both magnitude and direction. Examples include displacement, velocity, and force.

• Rectilinear motion - (C) Non-uniform motion
  Rectilinear motion refers to motion along a straight line, and it can be non-uniform when the speed changes, like an object speeding up or slowing down along a straight path.

• Circular motion - (B) Motion of satellite
  Circular motion involves an object moving along a circular path. The motion of a satellite around the Earth is an example of circular motion.

• Velocity - (B) m/s
  Velocity is the rate of change of displacement with time, and its unit is meters per second (m/s).

• Displacement - (D) m
  Displacement is the shortest distance between the initial and final position of an object, and its unit is meters (m).

• Acceleration - (A) m/s²
  Acceleration is the rate of change of velocity with time, and its unit is meters per second squared (m/s²).

• Retardation - (C) -m/s²
  Retardation is a type of acceleration that causes an object to slow down, and its unit is meters per second squared with a negative sign (-m/s²).

Vector- A physical quantity having a magnitude as well as direction is known as vector quantity. 
Odometer - an instrument for measuring the distance travelled by a wheeled vehicle. 
Acceleration of a body is defined as the rate of change of its velocity with time. 
Scalar - A physical quantity having only magnitude is known as a scalar quantity.

The correct answer is B as velocity-time graph we will get displacement travelled.as ,displacement=velocity/time

The graph shown above is not possible in case of Velocity - time graph. Graph may be straight  curved but not completely circular. 

Yes, a body can have a constant speed and still be accelerating.
Acceleration can be either due to change in speed or due to direction of motion or both.
Consider an example of a uniform circular motion. In a uniform circular motion, the body moves with a constant speed but we still say that it is accelerating due to the change in direction
This acceleration is called centripetal acceleration and is given as
a_c ​= −v²/r​
where v= constant speed
and r= radius of circle

If we get a curve line in the displacement – time graph, it means that the velocity of the object is changing over time. The velocity is not constant but varies at different points on the curve.

A curve in the displacement – time graph indicates that the object is undergoing acceleration, which in turn means that the velocity is changing. The shape of the curve can provide information about the nature of the change in velocity.

There are different cases when we can have a curve in the displacement – time graph:

• Increasing velocity: If the curve is upward sloping, it means that the velocity is increasing with time.


• Decreasing velocity: If the curve is downward sloping, it means that the velocity is decreasing with time.


• Changing acceleration: If the curve has varying slopes, it means that the acceleration is changing, and therefore, the velocity is also changing.

Therefore, if we get a curve line in the displacement – time graph, the velocity is non-uniform, as it is changing over time. Option B is the correct answer.

• Rate of change of velocity - (C) Acceleration
  The rate of change of velocity is known as acceleration. Acceleration measures how quickly velocity changes over time.

• Rate of change of displacement - (B) Velocity
  The rate of change of displacement is known as velocity. It measures how fast an object is moving in a particular direction.

• Rate of change of distance - (D) Speed
  The rate of change of distance is known as speed. Speed is the measure of how fast an object is moving regardless of direction.

• Rate of change of speed in circular path - (A) Uniform circular motion
  The rate of change of speed in a circular path refers to uniform circular motion, where the object moves in a circle at constant speed but with changing velocity due to the constant change in direction.

• Graph showing uniform velocity - (D) Straight line parallel to the x-axis
  A graph showing uniform velocity will be a straight line parallel to the x-axis, as the velocity remains constant over time.

• Graph showing uniformly accelerated velocity - (A) Straight line sloping upwards
  A graph showing uniformly accelerated velocity is a straight line sloping upwards, as the velocity increases uniformly over time.

• Graph showing uniformly retarded velocity - (C) Straight line sloping downwards
  A graph showing uniformly retarded velocity is a straight line sloping downwards, as the velocity decreases uniformly over time.

• Graph showing non-uniform motion - (B) Curved line
  A graph showing non-uniform motion will be a curved line, as the velocity is changing in a non-uniform way over time.

Acceleration is positive in the “down” direction, where “down” is where the nearest big source of gravity is.

In physics, acceleration is usually expressed as a vector, i.e. a direction and a magnitude. A magnitude is an absolute value, hence always positive.

Distance is a scalar quantity that refers to "how much ground an object has covered" during its motion.

As the body is moving in uniform motion, so the acceleration will be zero.
as acceleration is zero, the change in velocity is also zero.it means velocity will be the same in whole motion.