Science M.C.Q. [1 M]

3. Acceleration.

Explanation:
The rate of change of speed per unit time is termed as acceleration.

2. Uniform acceleration.

Explanation:
The displacement of the body in equal interval of time is unequal, but acceleration is constant. The acceleration will thus be uniform.

The speed is constant but velocity is not constant, because its direction goes on changing i.e., there is acceleration in the motion. So, we can say that the boy is in accelerated motion.

4. Equal to 1 or less than 1

Explanation:
Displacement is always smaller than or equal to displacement.

1. Uniform acceleration.

In merry-go-round, the speed is constant but velocity is not constant, because its direction goes on changing i.e., there is acceleration in the motion.
So, we can say that the boy is in accelerated motion.

2. Displacement.

3. A cheetah running 27 m/ s east

4. Car 4

Explanation:
The slope of the distance-time graph represents the velocity.
The slope for the car 4 is minimum, so its speed is also minimum.

3. A body moving with a constant velocity in an accelerated motion.

1. That the object moves towards the reference point

Explanation:
Negative slope of a displacement-time graph indicates negative velocity.
Velocity is measured negative when a body moves towards the reference point.

3. 37.88 km/ h

2. Its velocity

Explanation:
Velocity is a vector.
So, it gives the magnitude of speed and the direction of motion of the body as well.
Speed being a scalar, does not give the direction of motion.

4. Velocity of a moving body is its speed in a given direction.

4. Retardation is a scalar quantity

3. Stems

4. Speed

1. Velocity

Explanation:
Velocity of a body is the speed of the body defined along with the direction.

3. Four times as far

1. Direction of motion changes

Explanation:
An accelerating body is an object that is changing its velocity.
And since velocity is a vector that has both magnitude and direction, a change in either the magnitude or the direction constitutes a change in the velocity.

4. Angular speed

Explanation:
As an object moves around in a circle at constant speed (uniform circular motion), both the velocity and the acceleration change.
The magnitudes of the velocity and acceleration don't change, but since velocity and acceleration are vectors, the fact that their directions change means that they change.
Momentum is directly proportional to the velocity of the body and hence it changes.
In the uniform circular motion, the angular speed is same for all the particles,

2. Electrical energy into mechanical energy.

1. Acceleration increases velocity, retardation decreases it

3. Motion of a racing car on a circular track.

1. Uniform velociity

Explanation:
On a crowded road, depending on traffic conditions, the bus driver has to change its speed and direction of motion many times.
The driver will have to frequently apply brakes as well.
He might also have to accelerate the bus with different rates.
So, the velocity changes both by magnitude and direction.
Thus, uniform velocity is not attained in this case.

2. Uniform acceleration.

Explanation:
Velocity is measured in terms of distance per second, while acceleration is measured in terms of distance per square second.
Hence, uniform acceleration is the correct answer.

3. 26m

1. Clockwise direction.

4. The speed does not depend on the inital direction

2. 200m

2. Its velocity is necessarily changing

Explanation:
Acceleration is the time rate of change of velocity.

3. A car slowing down as it moves northward

Explanation:
The rate of change of velocity with respect to time is known as acceleration.
Negative acceleration means a decrease in velocity with respect to time.
If a car is moving northward and slowing down, the displacement will be along the north (positive), so the velocity will be positive until it gets stopped.
As the car is slowing down, the acceleration will be negative.

1. Weighing scale: Weight

Explanation:
An odometer is an instrument used in a vehicle to measure the distance covered by it.
Similarly, the weighing scale is an instrument used to measure the weight of an object.

1. If the car is moving on straight road.

Explanation:
In all other class, displacement can be less than distance.

2. Geographical South.

1. Will move forward.

Explanation:
The densest air in your passenger compartment is the ambient air. The least dense is your helium-filled balloon. When you accelerate, the ambient air will try to remain where it is and will appear to "slosh" toward the rear (if you can see the ambient air). Because the balloon has less inertia, it will be displaced by the heavier ambient air and will be forced forward in the passenger compartment.

1. Path length.

4. 8m

2. 28 metre per second

4. Yes, an example would be a falling object in a viscous medium, where the acceleration continuously decreases but velocity increases until a certain point.