Scalars and the Need for Vectors

Q.

A flywheel has moment of inertia 2 kgm². What constant torque is required to increase its speed from 4 rps to 12 rps in 8 sec?

1. 125.6 Nm

2. 12.56 Nm

3. 1256 Nm

4. 1.256 Nm

Q. 27. Which of the following does not possess the same dimensions as that of pressure 1) stress 2) bulk modulus 3) thrust 4) energy density

Q. 11. Half length of the chain of mass m and length is overhanging. What is speed of chain when it just slips off the smooth table?

Q. A uniform chain of mass 4 kg and length 2 m overhangs a smooth table with its one third part lying on the table. Find the speed of chain as it completely slips of the table. (Take g=10 m/s^2) (1) 10/3 m/s (2) 2 m/ (3) 2/3 m/s (4) 4/3 m/s

Q. Two identical blocks a and b each of mass are placed on smooth horizontal plane . At t=0 block b is given a velocity of 5m/s . Calculate the compression in the spring when velocity of A is 3m/s given spring constant of ideal spring is k

Q. 4.2 persons A and B of mass 80 kg and 60 kg respectively are sitting on the ends of a boat. The distance b/w them is 10m. The mass of the boat is 20kg. Find the displacement of the boat when the the 2 persons move towards each other.

Q. Pick out the only vector quantity in the following list : Temperature, pressure, impulse, time, power, total path length, energy, gravitational potential, coefficient of friction, charge.

Q. the relation between the displacement x and the time t of a particle moving under a cons†an t force is t=under root x+3 where x is in metre and t in sec. Determine the displacement of the particle at that ins†an t velocity is zero and the work done by the force in first 6seconds

Q. State, for each of the following physical quantities, if it is a scalar or a vector : volume, mass, speed, acceleration, density, number of moles, velocity, angular frequency, displacement, angular velocity.

Q. The work done to increase the from 30 m/s to 40 m/s, if the mass of the car is 1000 kg is (1) 350 J (3) 3.5 kJ (4) 3.5 J 31.) velocity of a car 2

Q. an athlete runs from one end to other end of semicircular track whose radius is 140 CM in 30 sec . what is the distance covered by the Marc and what is displacement at the end of the 75 sec

Q.

An athlete completes one round of a circular track of diameter 200 m in 40 s .what will be the distance covered and the displacement at the end of 2 minutes 20 s?

Q.

What does the slope of a velocity- time represent?

1. Displacement

2. Momentum

3. Acceleration

4. Distance

Q. why work is a scalar quantity as force and displacement are vectors

Q. Ravi apply a force of 10 Newton and moved box of 30cm in the direction of force how much the distance travelled by an object or a displacement in circular direction and also find how much was the force or work done by Ravi [take g=10 metre per second square ]

Q. Identify the vector quantity among the list of physical quantities given below:

1. Time
2. Velocity
3. Pressure
4. Mass

Q. why work is not a vector quantity as force and displacement are vector

Q. What is an unit vector and derive its formula.

Q. Derive an expression for K.E of an object. If the velocity of an object is doubled.what will be change in its K.E?

Q. Read each statement below carefully and state, with reasons and examples, if it is true or false : A scalar quantity is one that (a) is conserved in a process (b) can never take negative values (c) must be dimensionless (d) does not vary from one point to another in space (e) has the same value for observers with different orientations of axes.

Q. Water flows along horizontal pipe of non uniform cross section. The pressure is 1 cm of Hg where the velocity is 35 cm/s. At a point where the velocity is 65 cm/s , the pressure will be: A. 0.89 cm of Hg. B. 0.62 cm of Hg. C. 0.5 cm of Hg. D. 1 cm of Hg.

Q. how to find the direction by right hand thumb rule

Q. What is wieght of a 70kg body on the surface of a planet whose mass is 1/7th of that of earth and radius is half of earth?

Q. More than One Answer Type
एक से अधिक उत्तर प्रकार के प्रश्न

A uniform rod of mass 2 kg and length ℓ m is pivoted at one of its end such that it can swing freely in the vertical plane as shown in the figure. Which of the following option(s) are correct for rod at the vertical position, if it is released from horizontal position as shown?

2 kg द्रव्यमान व ℓ m लम्बाई की एक समरूप छड़ को इसके किसी एक सिरे पर इस प्रकार कीलकित किया जाता है कि यह चित्र में दर्शाए अनुसार ऊर्ध्वाधर तल में स्वतंत्र रूप से दोलन कर सके। यदि इसे दर्शायी गयी क्षैतिज स्थिति से छोड़ा जाता है, तब ऊर्ध्वाधर स्थिति पर छड़ के लिए निम्नलिखित में से कौनसा/कौनसे विकल्प सही है/हैं?

1. Angular acceleration is $\frac{3g}{4\ell }$
   
   कोणीय त्वरण $\frac{3g}{4\ell }$ है
2. Angular velocity is $\sqrt{\frac{4g}{3\ell }}$
   
   कोणीय वेग $\sqrt{\frac{4g}{3\ell }}$ है
3. Angular acceleration is zero
   
   कोणीय त्वरण शून्य है
4. Angular velocity is $\sqrt{\frac{3g}{\ell }}$
   
   कोणीय वेग $\sqrt{\frac{3g}{\ell }}$ है

Q. A body of mass 10 kg moving on a circular pathwith a uniform speed 10 m/s. Magnitude of change in linear momentum when it turns through the 1/3 rd revolution is

Q. Pick out the two scalar quantities in the following list : force, angular momentum, work, current, linear momentum, electric field, average velocity, magnetic moment, relative velocity

Q. 3.An object is moving with speed 10 m/s along thedirection of a vector 4i -3j. Velocity of the objectis

Q.

When a force is applied on an object, then that object exerts an equal and opposite force on the other body, then how come is it posssible to stop a body by applying a force ?

Q. A body is initially at rest. It undergoes one dimensional motion with cons†an t acceleration. The power delivered to it at time t is proportional to?

Q. Ravi apply a force of 10 Newton and moved box of 30cm in the direction of force how much the distance travelled by an object or a displacement in circular direction and also find how much was the force or work done by Ravi [take g=10 metre per second square ]