Test: Newton’s First Law of Motion - JEE MCQ

Given:
Mass of the car (m) = 1000 kg
Initial velocity (u) = 20 m/s
Final velocity (v) = 0 m/s
Time (t) = 4 s

Using the equation of motion: v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time, we can rearrange the equation to solve for the acceleration.

0 = 20 m/s + a * 4 s
a = -5 m/s² (negative sign indicates deceleration)

Since the car comes to a stop, its final velocity is 0 m/s. We can use Newton's second law, F = ma, where F is the force, m is the mass, and a is the acceleration, to find the magnitude of the force.

F = 1000 kg * (-5 m/s²)
F = -5000 N

The magnitude of the force is 5000 N. However, since the force is acting in the opposite direction to the car's motion (deceleration), we take the magnitude as the answer.

Therefore, the correct answer is A: 5000N.

Given:
Mass of the block (m) = 2 kg
Force applied (F) = 8 N
Time (t) = 5 s

Since no external forces are acting on the block other than the applied force, the net force is equal to the applied force. Using Newton's second law, F = ma, where F is the force, m is the mass, and a is the acceleration.

8 N = 2 kg * a
a = 4 m/s²

Now, we can use the equation of motion: v = u + at, where v is the final velocity, u is the initial velocity (which is 0 m/s), a is the acceleration, and t is the time.

v = 0 + 4 m/s² * 5 s
v = 20 m/s

Therefore, the final velocity of the block is 20 m/s.

Force of inertia = ma

Let the masses be 1x and 5x

Force of inertia for 1st body= 1x * a

Force of inertia for 2nd = 5x * a

Ratio= x * a / 5x * a = 1:5

Additional Information: The inability of a body to change it’s state of rest or uniform motion is called inertia.

F = F1 + F2 + F3 = ( 20i + 30j) N+(8i - 50j) N+(2i +2 j) N

=(20+8+2)i+(30-50+2)j

F=30i - 18j

F = ma

Substituting F and m = 6 kg (given) in the above equation we get,

30i - 18j = 6*a

A = 5i - 3j

Hence (b) is correct choice

According to newton's first law of motion, an object either remains at rest or continues to move at a constant velocity, unless acted upon by an external net force.
Therefore The force required to keep the body moving with the same velocity is zero.

To calculate the acceleration of the object, we can use Newton's second law of motion, which states that the force acting on an object is equal to the mass of the object multiplied by its acceleration.

Given:
Mass of the object (m) = 5 kg
Initial velocity (u) = 10 m/s
Force applied (F) = -30 N (opposite direction of motion)

Using Newton's second law, F = ma,
we can rearrange the equation to solve for acceleration (a).
-30 N = 5 kg * a
a = -6 m/s² (negative sign indicates the opposite direction)

Therefore, the acceleration of the object is 6 m/s² in the opposite direction of its initial motion.

The correct answer is a) 6 m/s².

• It is usually seen that during rainy days we tend to slip because rainwater acts as a lubricant between our feet and the ground.  

• This lubrication (rainwater) converts dry friction into fluid friction. 

• That is, the friction between feet and ground reduces, making us slip.

Therefore, due to less friction, we slip on a rainy day.

When the bus moves, the passenger's body comes into a state of motion but when the bus stops the lower part of the body which is in contact with the floor comes into a state of rest whereas the upper part of the body still remains in the state of motion and because of this the upper part of the body falls in the forward direction. This is due to the presence of inertia. 

Hence the correct answer is C.

Given: 

Speed of the particle after a time 2T, 

• Newton’s first law of inertia states that an object at rest or in motion tends to stay at rest or moving with constant motion unless enacted upon by an unbalanced force. 

• The law of inertia relates to the sport of cycling due to the fact that the cyclist is in constant motion when on the cycle. 

• The motion of the bike is caused by the rider pressing down upon the pedals, which, in turn, enables the rider to accelerate on the bike. 

• As well, the cyclist will continue to move unless enacted upon by an opposing unbalanced force, such as the force of friction on the bike tires, when the bike decelerates to a stop. 

• The Law of Inertia is also displayed when the cyclist begins to move on the bicycle from a stop. 

• The action is related to the concept of Inertia for the reason that the cyclist is applying an unbalanced force to the bicycle pedals when not in motion. As a result, the bicycle would gain acceleration and therefore begin to move.

Therefore the correct answer is B.