K.E. in Relativistic Physics

Q.

What are the factors on which the kinetic energy of a body depends?

Q. There is no slipping between the two blocks. What is force of friction between two blocks?

1. Zero
2. 12N
3. 9N
4. 6N

Q.

A horse and a dog are running with the same speed. The horse will possess more kinetic energy. Give the reason for the same.

Q.

What kind of energy is possessed by the following:

A speeding car:

Q.

Write a short note on kinetic energy.

Q.

Calculate the kinetic energy of a body of mass $15kg$ if it is moving with a velocity of$8m{s}^{-1}$.

Q.

A van is moving with a uniform velocity of $15m{s}^{-1}$. What is the kinetic energy of a boy of mass $40kg$ sitting in the van?

Q. The kinetic energy of a particle moving along a circle of radius $R$ depends on distance $\left(s\right)$ as $K=A{s}^2$ where $A$ is a constant.

The tangential force acting on the particle is

1. $2mAs$
2. $As$
3. $mAs$
4. $2As$

Q. $v-t$ graph of a particle moving along x axis is shown in figure. Mass of the particle = 4 kg. Work done by all the forces acting on particle between $t=3$ to $t=6$ is

1. 12 J
2. 24 J
3. 8 J
4. 32 J

Q.

Give an expression for kinetic energy of an object.

Q. A force $F=(2+x)$ acts on a particle in x-direction where $F$ is in newton and $x$ in meter. Find the work done by this force during a displacement from $x=1.0$ m to $x=2.0m$.

1. $7J$
2. $3.5J$
3. $4.5J$
4. $5.5J$

Q.

What are the two factors on which the kinetic energy depends? Explain.

Q. A block of mass $2kg$ is placed on the floor. Force of $2.8N$ is applied to it. The coefficient of static friction is $0.4$. The force of friction between the block and the floor (taking $g=10m/s^2$) is

1. $2.8N$
2. Zero
3. $8N$
4. $2N$

Q. A cyclist moving at a speed of $20$ m/s takes a turn, if he doubles his speed then change of overturn

1. is halved
2. is doubled
3. becomes 1/4 times
4. becomes four times

Q. A $0.50kg$ object moves in a horizontal circular track with a radius of $2.5m$. An external force of $3.0N$, always tangent to the track, causes the object to speed up as it goes around. The work done by the external force as the mass makes one revolution is:

1. $24J$
   
2. $47J$
   
3. $58J$
   
4. $67J$
   

Q. (1) : In uniform circular motion the kinetic energy of the body is constant.
(2) : In uniform circular motion the tangential force is zero.

1. Both 1 and 2 are true and 2 is correct explanation of 1
2. Both 1 and 2 are true and 2 is not correct explanation of 1
3. 1 is true and 2 is false
4. 1 is false and 2 is true

Q. A block of mass 2 kg is placed on the floor. The coefficient of static friction is ${\mu }_s$=0.4. If a force of 2.8 N is applied on the block parallel to the floor, the force of friction between the block and floor (taking $g=10m/{sec}^2$)

1. 2.8N
2. 8N
3. 2N
4. Zero

Q. A time varying net force acts on a $8.0kg$ block. Particle's displacement is given by $X=A{t}^2+Bt+C$ $(A=2m/s^2,B=6m/s,C=4m)$. Find work done on the block in first $4s$ of motion.

1. 1947
2. 1857
3. 1792
4. 1869

Q. A block of mass m is given a kick on frozen pond, imparting an initial speed of $v=4m/s$. Coefficient of friction between block and ice is ${\mu }_K=0.5$. Find the distance the block moves before stopping.

1. 2.4 m
2. 0.8 m
3. 3.2m
4. 1.6 m

Q.

If two airplanes, one big and one small, travel at the same speed, the smaller one has more kinetic energy.

1. True
2. False

Q. If 2 persons A and B of mass M are sitting inside a bus moving with a constant velocity v. Person C is standing on the road watching the bus go.What would be the Kinetic Energy of A told by B and C respectively?

1. $\frac{\left(m{v}^2\right)}{2}$, $\frac{\left(m{v}^2\right)}{2}$
2. 0, $\frac{\left(m{v}^2\right)}{2}$
3. $\frac{\left(m{v}^2\right)}{2}$, 0
4. 0, 0

Q. A block of man 3 kg is placed on the floor of coefficient of static friction is 0.4. The force 3.5 N applied on the block. Calculate the force of friction and discuss the motion & the body.

1. 12.76N
2. 11.76N
3. 3.5N
4. None of the above

Q. A marble block of mass 2kg lying on ice when given a velocity of $6m{s}^{-1}$ is stopped by friction in 10s. Then the coefficient of friction is ( Take $g=10m{s}^{-2}$)

1. 0.06
2. 0.03
3. 0.01
4. 0.04

Q. A 60 kg body is pushed horizonatally With just enough force to start it moving across a floor and the same force continues to act afterwards. The coefficient of static friction and sliding friction are 0.5 and 0.4 respectively. The acceleration of the body is

1. $6m/s^2$
2. $4.9m/s^2$
3. $3.92m/s^2$
4. $1m/s^2$

Q. If the velocity of a car is tripled its KE is:

1. Doubled
2. Tripled
3. Increased by 9 times
4. Increase 15 times

Q. A block of mass 0.1 kg is held against a wall by applying a horizontal force of 5N on the block. If the co-efficient of friction between the block and the wall is 0.5, the magnitude of frictional force acting on the block is

1. 2.5 N
2. 0.98 N
3. 4.9 N
4. 0.49 N

Q.

If the velocity of an object is decreased, its_________ energy will be affected.

Q. A time varying net force acts on a $8.0kg$ block. Particle's displacement is given by $X=A{t}^2+Bt+C$ $(A=2m/s^2,B=6m/s,C=4m)$. Find work done on the block in first $4s$ of motion.

1. 1947
2. 1857
3. 1792
4. 1869

Q. A block of mass $1000kg$ lying steady on the horizontal surface of a table needs $200N$ horizontal force to came into motion. What is the coefficient of static friction between the block and the surface of table?
[take $g=10{ms}^{-2}$]

1. $0.2$
2. $0.02$
3. $0.5$
4. $0.05$

Q.

Explain the term ‘Kinetic Energy’.