Test: Motion: 1 - UPSC

The slope of the velocity-time graph determines the acceleration.

Balanced forces are two forces acting in opposite directions on an object, and equal in size. Anytime there is a balanced force on an object, the object stays still or continues moving continues to move at the same speed and in the same direction.

Radius of truck = r = 140m 
circumfarance
Time taken to cover the distance = t = 5 min 52 sec = 352 sec
Since it complete 2 rounds, therefor distance it travels is 2 times of circumference. 

Friction is a resisting force that acts on a body to prevent or retard its motion. Friction force always acts tangent to the surface at points of contact. Friction force acts opposite to the direction of motion.

Forces are said to be balanced when two equal and opposite forces acts on an object which makes net force to be zero. Balanced forces are acting means object will be rest. When unbalanced forces are acting on object it starts moving in the direction of force. Example a book kept on table has two forces gravitational force acting downwards and normal force acting upwards. As two forces are equal and opposite the net force will be zero and object remains at rest.

So option D is correct

The correct answer is C as When unbalanced forces act on a body, the body: as it must experience acceleration by the force applied on it.

Torque is the rotational analogue of force and angular velocityis the rotational analogue of linear velocity in rotational mechanics and when no external force act on the body, its velocity is constant. similarly when no torque acts on a body, its angular velocity is constant.

So option D is correct.

The acceleration mentioned is due to the force of gravity. This is a force of attraction based on the mass of an object and the distance between the two objects Newton's law of universal gravitation. Generally on the surface of the earth we treat this as 9.8 m/sec^2 or 32 ft/sec^2. The way that Einstein describes it is that mass curves spacetime, thus space itself is pushing down on the falling object and is the cause of the force. 

So option C is correct.

Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied. It also determines the strength of its mutual gravitational attraction to other bodies. The basic SI unit of mass is the kilogram (kg).

If the degree of force acting on the object is the same ( F = ma) , then as mass increases, acceleration will go down ( a = F / m) . 
So, option ( c) decrease is the correct answer.

GIVEN:-
FORCE PRODUCED IN THE BODY =  F
ACCELERATION PRODUCED WITH FORCE F =  a
ACCELERATION PRODUCED IN OTHER BODY BY SAME FORCE = 4a

To find : Mass of the other body where acceleration produced is 4a

First body -
F = m * a
f/a = m  --------- (eq.01)

Second body - 
Let mass be x
F = X * 4a
F/4a = X   ------(eq.02)

Solving the equation we get-
X = ¼ m

Newton's first law of motion follows that if the body is in rest or moving with the uniform velocity it will be in rest or uniform velocity unless or until an external force is applied on the body to change its state of motion. So when the bike suddenly accelerates the body of pillion is not able to make the body accelerate so fast because when the bike was running his body was also moving with that motion only. So when the bike suddenly accelerates it was not able to move with that acceleration.

"Vector quantities have both magnitude and direction. Scalar quantities have only magnitude."

The displacement is a vector quantity (magnitude and direction) that describes the difference between the final and initial positions of a moving object. It is the shortest distance moved in a certain direction. The displacement is the vector AD whose magnitude if 5 km and its direction is to the east.

SPEED = DISTANCE / TIME 
DISTANCE = 100M 
TIME = 50 SEC 
THEN, SPEED =100M / 50 SEC 
SPEED = 2 M / S

Speedometer is device that measure the speed of vehicle, at any instant of time i.e measure instantaneous speed.

Speed is a scalar quantity which means it has only magnitude and no direction, btw velocity is a vector quantity which means it has both magnitude and no direction.

It's safe to say that the answer is uniform speed because the question didn't mention about the particle covering equal distances in equal intervals of time in a particular direction. Therefore, the answer is uniform speed.

Had the question have mentioned 'in a particular direction' then the answer would have been uniform velocity.

Therefore, the answer is UNIFORM SPEED.

A curved line in a speed - time graph means non - uniform motion. In speed - time graph, uniform motion is represented by straight line parallel to time zone . We know that, slope of the velocity - time graph gives the acceleration of the body. If the velocity Time graph is a curved line, this means it's slope changes at every instant. Thus the body is said to be in non - uniform motion. 

So option A is correct

AS, d=120m (length of train)

t=6 sec (to pass the pole)

v=?

Therefore,

 v=d\t

  =120\6

  =20m\s

As, The train is 120 m long and bridge is 50 m long = {120+ 50 = 170 m }                                                                                    So, Time taken = distance/speed   

         = 170/20 

         = 8.5 seconds                                                                                            

The correct option is B.
For a body moving at a uniform velocity you can calculate the speed by dividing the distance traveled by the amount of time it took, for example one mile in 1/2 hour would give you 2 miles per hour.
In order to find the velocity of the moving object, you will need to divide the change in position by the change in time. Specify the direction moved, and you have the average velocity.
Calculating acceleration involves dividing velocity by time — or in terms of SI units, dividing the meter per second [m/s] by the second [s]. Dividing distance by time twice is the same as dividing distance by the square of time. Thus the SI unit of acceleration is the meter per second squared 
Average speed is calculated by dividing distance by time (e.g. miles/hour). Okay we're going to talk about average speed, instantaneous speed is the distance that you're covering at a specific time. So 100 kilometers an hour, average speed is the total distance you're going to cover over a period of time.

Satellites revolve around their planets in almost circular orbits with constant speed. Thus, during their motion, the speed remains constant, while the direction of motion changes continuously. As a result, there is a change in their velocity. Moon moves in uniform circular motion around the earth. It is the force of gravity of the earth which keeps the moon in circular orbit around it. The motion of any particle on the arm of a clock is circular as thus uniform motion.

first equation of motion is : v = u + at

Case of Accelerated Motion
Uniform Acceleration

A body under constant acceleration is uniformly accelerated motion. This is when a constant external force is applied to the body. The direction of acceleration is very important in the change of velocity. However, the direction of acceleration of a body may not be same as the direction of its motion. For example, if a car travels at a speed of 60 km/hour then it will cover a distance of 1 km/minute. Here the motion of car acceleration is uniform.

Motion is an athlete running 100m along a straight track. Linear motion is the most basic of all motion. According to Newton's first law of motion, objects that do not experience any net force will continue to move in a straight line with a constant velocity until they are subjected to a net force.

So option D is correct.

The area under the velocity time graph will give us the displacement of an object and the slope gives the acceleration

we should find the area under the graph , if the graph is irregular we need to split it into parts and finally add them and if the shape is not at all regular we should go for integration