Laws of Motion Practice Questions - DPP for JEE

 Page 1


PART-I (Single Correct MCQs)
1. A player stops a football weighing 0.5 kg which comes flying towards
him with a velocity of 10m/s. If the impact lasts for 1/50th sec. and the
ball bounces back with a velocity of 15 m/s, then the average force
involved is
(a) 250 N
(b) 1250 N
(c) 500 N
(d) 625 N
2. A mass ‘m’ is supported by a massless string wound around a uniform
hollow cylinder of mass m and radius R. If the string does not slip on
the cylinder, with what acceleration will the mass release?
(a)
Page 2


PART-I (Single Correct MCQs)
1. A player stops a football weighing 0.5 kg which comes flying towards
him with a velocity of 10m/s. If the impact lasts for 1/50th sec. and the
ball bounces back with a velocity of 15 m/s, then the average force
involved is
(a) 250 N
(b) 1250 N
(c) 500 N
(d) 625 N
2. A mass ‘m’ is supported by a massless string wound around a uniform
hollow cylinder of mass m and radius R. If the string does not slip on
the cylinder, with what acceleration will the mass release?
(a)
(b)
(c)
(d) g
3. A 40 kg slab rests on a frictionless floor as shown in
the figure. A 10 kg block rests on the top of the
slab. The static coefficient of friction between the
block and slab is 0.60 while the coefficient of
kinetic friction is 0.40. The 10 kg block is acted upon by a horizontal
force of 100 N. If g = 9.8 m/s
2
, the resultaing acceleration of the slab
will be
(a) 0.98 m/s
2
(b) 1.47 m/s
2
(c) 1.52 m/s
2
(d) 6.1 m/s
2
4. A satellite in a force free space sweeps stationary interplanetary dust at
a rate (dM/dt) = av. The acceleration of satellite is
(a)
(b)
(c)
(d) – av
2
5. A monkey is decending from the branch of a tree with constant
acceleration. If the breaking strength is 75% of the weight of the
monkey, the minimum acceleration with which monkey can slide down
without breaking the branch is
Page 3


PART-I (Single Correct MCQs)
1. A player stops a football weighing 0.5 kg which comes flying towards
him with a velocity of 10m/s. If the impact lasts for 1/50th sec. and the
ball bounces back with a velocity of 15 m/s, then the average force
involved is
(a) 250 N
(b) 1250 N
(c) 500 N
(d) 625 N
2. A mass ‘m’ is supported by a massless string wound around a uniform
hollow cylinder of mass m and radius R. If the string does not slip on
the cylinder, with what acceleration will the mass release?
(a)
(b)
(c)
(d) g
3. A 40 kg slab rests on a frictionless floor as shown in
the figure. A 10 kg block rests on the top of the
slab. The static coefficient of friction between the
block and slab is 0.60 while the coefficient of
kinetic friction is 0.40. The 10 kg block is acted upon by a horizontal
force of 100 N. If g = 9.8 m/s
2
, the resultaing acceleration of the slab
will be
(a) 0.98 m/s
2
(b) 1.47 m/s
2
(c) 1.52 m/s
2
(d) 6.1 m/s
2
4. A satellite in a force free space sweeps stationary interplanetary dust at
a rate (dM/dt) = av. The acceleration of satellite is
(a)
(b)
(c)
(d) – av
2
5. A monkey is decending from the branch of a tree with constant
acceleration. If the breaking strength is 75% of the weight of the
monkey, the minimum acceleration with which monkey can slide down
without breaking the branch is
(a) g
(b)
(c)
(d)
6. A plank with a box on it at one end is gradually raised about the other
end. As the angle of inclination with the horizontal reaches 30º the box
starts to slip and slides 4.0 m down
the plank in 4.0s. The coefficients of static and kinetic
friction between the box and the plank will be,
respectively :
(a) 0.6 and 0.5 (b) 0.5 and 0.6
(c) 0.4 and 0.3
(d) 0.6 and 0.6
7. A stationary body of mass 3 kg explodes into three equal pieces. Two of
the pieces fly off in two mutually perpendicular directions, one with a
velocity of  and the other with a velocity of  If the
explosion occurs in 10
–4
 s, the average force acting on the third piece in
newton is
(a)
(b)
(c)
(d)
8. A bullet is fired from a gun. The force on the bullet is given by F = 600
– 2 × 10
5
 t where, F is in newton and t in second. The force on the bullet
becomes zero as soon as it leaves the barrel. What is the average
impulse imparted to the bullet?
(a) 1.8 N-s
Page 4


PART-I (Single Correct MCQs)
1. A player stops a football weighing 0.5 kg which comes flying towards
him with a velocity of 10m/s. If the impact lasts for 1/50th sec. and the
ball bounces back with a velocity of 15 m/s, then the average force
involved is
(a) 250 N
(b) 1250 N
(c) 500 N
(d) 625 N
2. A mass ‘m’ is supported by a massless string wound around a uniform
hollow cylinder of mass m and radius R. If the string does not slip on
the cylinder, with what acceleration will the mass release?
(a)
(b)
(c)
(d) g
3. A 40 kg slab rests on a frictionless floor as shown in
the figure. A 10 kg block rests on the top of the
slab. The static coefficient of friction between the
block and slab is 0.60 while the coefficient of
kinetic friction is 0.40. The 10 kg block is acted upon by a horizontal
force of 100 N. If g = 9.8 m/s
2
, the resultaing acceleration of the slab
will be
(a) 0.98 m/s
2
(b) 1.47 m/s
2
(c) 1.52 m/s
2
(d) 6.1 m/s
2
4. A satellite in a force free space sweeps stationary interplanetary dust at
a rate (dM/dt) = av. The acceleration of satellite is
(a)
(b)
(c)
(d) – av
2
5. A monkey is decending from the branch of a tree with constant
acceleration. If the breaking strength is 75% of the weight of the
monkey, the minimum acceleration with which monkey can slide down
without breaking the branch is
(a) g
(b)
(c)
(d)
6. A plank with a box on it at one end is gradually raised about the other
end. As the angle of inclination with the horizontal reaches 30º the box
starts to slip and slides 4.0 m down
the plank in 4.0s. The coefficients of static and kinetic
friction between the box and the plank will be,
respectively :
(a) 0.6 and 0.5 (b) 0.5 and 0.6
(c) 0.4 and 0.3
(d) 0.6 and 0.6
7. A stationary body of mass 3 kg explodes into three equal pieces. Two of
the pieces fly off in two mutually perpendicular directions, one with a
velocity of  and the other with a velocity of  If the
explosion occurs in 10
–4
 s, the average force acting on the third piece in
newton is
(a)
(b)
(c)
(d)
8. A bullet is fired from a gun. The force on the bullet is given by F = 600
– 2 × 10
5
 t where, F is in newton and t in second. The force on the bullet
becomes zero as soon as it leaves the barrel. What is the average
impulse imparted to the bullet?
(a) 1.8 N-s
(b) zero
(c) 9 N-s
(d) 0.9 N-s
9. Three forces start acting simultaneously on a particle moving with
velocity, . These forces are represented in magnitude and direction
by  the three sides of a triangle  ABC. The particle will now move with
velocity
(a) less than 
(b) greater than 
(c) |v| in the direction of the largest force BC
(d) , remaining unchanged
10. A block is kept on a inclined plane of inclination ? of
length l. The velocity of particle at the bottom of inclined is (the
coefficient of friction is µ)
(a)
(b)
(c)
(d)
11. A ball of mass 10 g moving perpendicular to the plane of the wall
strikes it and rebounds in the same line with the same velocity. If the
impulse experienced by the wall is 0.54 Ns, the velocity of the ball is
(a) 27 ms
–1
(b) 3.7 ms
–1
(c) 54 ms
–1
(d) 37 ms
–1
12. A block of mass m is placed on a surface with a vertical cross section
given by  If the coefficient of friction is 0.5, the maximum
height above the ground at which the block can be placed without
slipping is:
Page 5


PART-I (Single Correct MCQs)
1. A player stops a football weighing 0.5 kg which comes flying towards
him with a velocity of 10m/s. If the impact lasts for 1/50th sec. and the
ball bounces back with a velocity of 15 m/s, then the average force
involved is
(a) 250 N
(b) 1250 N
(c) 500 N
(d) 625 N
2. A mass ‘m’ is supported by a massless string wound around a uniform
hollow cylinder of mass m and radius R. If the string does not slip on
the cylinder, with what acceleration will the mass release?
(a)
(b)
(c)
(d) g
3. A 40 kg slab rests on a frictionless floor as shown in
the figure. A 10 kg block rests on the top of the
slab. The static coefficient of friction between the
block and slab is 0.60 while the coefficient of
kinetic friction is 0.40. The 10 kg block is acted upon by a horizontal
force of 100 N. If g = 9.8 m/s
2
, the resultaing acceleration of the slab
will be
(a) 0.98 m/s
2
(b) 1.47 m/s
2
(c) 1.52 m/s
2
(d) 6.1 m/s
2
4. A satellite in a force free space sweeps stationary interplanetary dust at
a rate (dM/dt) = av. The acceleration of satellite is
(a)
(b)
(c)
(d) – av
2
5. A monkey is decending from the branch of a tree with constant
acceleration. If the breaking strength is 75% of the weight of the
monkey, the minimum acceleration with which monkey can slide down
without breaking the branch is
(a) g
(b)
(c)
(d)
6. A plank with a box on it at one end is gradually raised about the other
end. As the angle of inclination with the horizontal reaches 30º the box
starts to slip and slides 4.0 m down
the plank in 4.0s. The coefficients of static and kinetic
friction between the box and the plank will be,
respectively :
(a) 0.6 and 0.5 (b) 0.5 and 0.6
(c) 0.4 and 0.3
(d) 0.6 and 0.6
7. A stationary body of mass 3 kg explodes into three equal pieces. Two of
the pieces fly off in two mutually perpendicular directions, one with a
velocity of  and the other with a velocity of  If the
explosion occurs in 10
–4
 s, the average force acting on the third piece in
newton is
(a)
(b)
(c)
(d)
8. A bullet is fired from a gun. The force on the bullet is given by F = 600
– 2 × 10
5
 t where, F is in newton and t in second. The force on the bullet
becomes zero as soon as it leaves the barrel. What is the average
impulse imparted to the bullet?
(a) 1.8 N-s
(b) zero
(c) 9 N-s
(d) 0.9 N-s
9. Three forces start acting simultaneously on a particle moving with
velocity, . These forces are represented in magnitude and direction
by  the three sides of a triangle  ABC. The particle will now move with
velocity
(a) less than 
(b) greater than 
(c) |v| in the direction of the largest force BC
(d) , remaining unchanged
10. A block is kept on a inclined plane of inclination ? of
length l. The velocity of particle at the bottom of inclined is (the
coefficient of friction is µ)
(a)
(b)
(c)
(d)
11. A ball of mass 10 g moving perpendicular to the plane of the wall
strikes it and rebounds in the same line with the same velocity. If the
impulse experienced by the wall is 0.54 Ns, the velocity of the ball is
(a) 27 ms
–1
(b) 3.7 ms
–1
(c) 54 ms
–1
(d) 37 ms
–1
12. A block of mass m is placed on a surface with a vertical cross section
given by  If the coefficient of friction is 0.5, the maximum
height above the ground at which the block can be placed without
slipping is:
(a)
(b)
(c)
(d)
13. A block of mass m is connected to another block of mass M by  a spring
(massless) of spring constant k. The block are kept on a smooth
horizontal plane. Initially the blocks are at rest and the spring is
unstretched. Then a constant force F starts acting on the block of mass
M to pull it. Find the force of the block of mass m.
(a)
(b)
(c)
(d)
14. Two particles of mass m each are tied at the ends of a light string of
length 2a. The whole system is kept on a frictionless horizontal surface
with the string held tight so that each mass is at a distance ‘a’ from the
centre P (as shown in the figure).
Now, the mid-point of the string is pulled vertically
upwards with a small but constant force F. As a
result, the particles move towards each other on
the surface. The magnitude of acceleration, when
the separation between them becomes 2x, is
(a)