Physics-
General
Easy
Question
When the mass of a system is variable, a thrust force has to be applied on it in addition to all other forces acting on it. This thrust force is given by 
Here 
is the relative velocity with which the mass d m either enters or leaves the system. A car has total mass 50 kg. Gases are ejected from this backwards with relative velocity 20 m/s. The rate of ejection of gas is 2 kg/total mass of gas is 20 kg. Coefficient of friction between the car and road is 
= 0.1 Car will start moving after time t = . .. second:
- 4
- 10
- 5
- 8
The correct answer is: 10
Related Questions to study
physics-
In an oblique collision component parallel to common tangent remains unchanged while along common normal direction, relative velocity of separation becomes e times the relative velocity of approach. A ball collides at B with velocity 10 m/s at 30° with vertical. There is a flag at A and a wall at C. Collision of ball with ground is perfectly inelastic (e = 0) and that with wall is elastic (e = 1). Given AB = BC = 10m. The ball will collide with the flag after time t = ....s
In an oblique collision component parallel to common tangent remains unchanged while along common normal direction, relative velocity of separation becomes e times the relative velocity of approach. A ball collides at B with velocity 10 m/s at 30° with vertical. There is a flag at A and a wall at C. Collision of ball with ground is perfectly inelastic (e = 0) and that with wall is elastic (e = 1). Given AB = BC = 10m. The ball will collide with the flag after time t = ....s
physics-General
physics-
If net force on a system in a particular direction is zero (say in horizontal direction) we can apply: 
Here R stands for the masses which are moving towards right and L for the masses towards left, x is displacement, v is velocity and a the acceleration (all with respect to ground). A small block of mass m = 1 kg is placed over a wedge of mass M = 4 kg as shown in figure. Mass m is released from rest. All surfaces are smooth. Origin O is as shown. At the same instant reaction on the wedge from the ground is N
If net force on a system in a particular direction is zero (say in horizontal direction) we can apply: Here R stands for the masses which are moving towards right and L for the masses towards left, x is displacement, v is velocity and a the acceleration (all with respect to ground). A small block of mass m = 1 kg is placed over a wedge of mass M = 4 kg as shown in figure. Mass m is released from rest. All surfaces are smooth. Origin O is as shown. At the same instant reaction on the wedge from the ground is N
physics-General
physics-
If net force on a system in a particular direction is zero (say in horizontal direction) we can apply: Here R stands for the masses which are moving towards right and L for the masses towards left, x is displacement, v is velocity and a the acceleration (all with respect to ground). A small block of mass m = 1 kg is placed over a wedge of mass M = 4 kg as shown in figure. Mass m is released from rest. All surfaces are smooth. Origin O is as shown. Normal reaction between the two blocks at an instant when absolute acceleration of m is 
m/s2 at 60° with horizontal is N. Normal reaction at this instant is making 
with horizontal:
If net force on a system in a particular direction is zero (say in horizontal direction) we can apply: Here R stands for the masses which are moving towards right and L for the masses towards left, x is displacement, v is velocity and a the acceleration (all with respect to ground). A small block of mass m = 1 kg is placed over a wedge of mass M = 4 kg as shown in figure. Mass m is released from rest. All surfaces are smooth. Origin O is as shown. Normal reaction between the two blocks at an instant when absolute acceleration of m is m/s2 at 60° with horizontal is N. Normal reaction at this instant is making with horizontal:
physics-General
physics-
If net force on a system in a particular direction is zero (say in horizontal direction) we can apply: Here R stands for the masses which are moving towards right and L for the masses towards left, x is displacement, v is velocity and a the acceleration (all with respect to ground). A small block of mass m = 1 kg is placed over a wedge of mass M = 4 kg as shown in figure. Mass m is released from rest. All surfaces are smooth. Origin O is as shown. The block will strike the x–axis at x = ....m :–
If net force on a system in a particular direction is zero (say in horizontal direction) we can apply: Here R stands for the masses which are moving towards right and L for the masses towards left, x is displacement, v is velocity and a the acceleration (all with respect to ground). A small block of mass m = 1 kg is placed over a wedge of mass M = 4 kg as shown in figure. Mass m is released from rest. All surfaces are smooth. Origin O is as shown. The block will strike the x–axis at x = ....m :–
physics-General
physics-
If net force on a system in a particular direction is zero (say in horizontal direction) we can apply: Here R stands for the masses which are moving towards right and L for the masses towards left, x is displacement, v is velocity and a the acceleration (all with respect to ground). A small block of mass m = 1 kg is placed over a wedge of mass M = 4 kg as shown in figure. Mass m is released from rest. All surfaces are smooth. Origin O is as shown. Final velocity of the wedge is m/s :–
If net force on a system in a particular direction is zero (say in horizontal direction) we can apply: Here R stands for the masses which are moving towards right and L for the masses towards left, x is displacement, v is velocity and a the acceleration (all with respect to ground). A small block of mass m = 1 kg is placed over a wedge of mass M = 4 kg as shown in figure. Mass m is released from rest. All surfaces are smooth. Origin O is as shown. Final velocity of the wedge is m/s :–
physics-General
physics-
When two bodies collide normally, they exert equal and opposite impulses on each other. Impulse = change in linear momentum. Coefficient of restitution between two bodies is given by :– 
for elastic collision Two bodies collide as shown in figure. During collision they exert impulse of magnitude J on each other. For what values of J (in N–s) the 2 kg block will change its direction of velocity :
When two bodies collide normally, they exert equal and opposite impulses on each other. Impulse = change in linear momentum. Coefficient of restitution between two bodies is given by :– for elastic collision Two bodies collide as shown in figure. During collision they exert impulse of magnitude J on each other. For what values of J (in N–s) the 2 kg block will change its direction of velocity :
physics-General
physics-
When two bodies collide normally, they exert equal and opposite impulses on each other. Impulse = change in linear momentum. Coefficient of restitution between two bodies is given by :– for elastic collision Two bodies collide as shown in figure. During collision they exert impulse of magnitude J on each other. If the collision is elastic, the value of J is N–s :
When two bodies collide normally, they exert equal and opposite impulses on each other. Impulse = change in linear momentum. Coefficient of restitution between two bodies is given by :– for elastic collision Two bodies collide as shown in figure. During collision they exert impulse of magnitude J on each other. If the collision is elastic, the value of J is N–s :
physics-General
physics-
A police car moving at
, changes a motorcyclist. The police man sounds his horn at 176 Hz, while both of them move towards a stationary siren of frequency 165 Hz. Calculate the speed of the motorcycle, if it is given that he does not observe any beats.
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physics-General
physics-
Figure here shown an incident pulse 
reflected from a rigid support. Which one of 
represents the reflected pulse correctly
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physics-General
maths-
The tangent at the point P(x1, y1) to the parabola y2 = 4ax meets the parabola y2 = 4a(x + b) at Q and R, the coordinates of the mid-point of QR are
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maths-General
maths-
If P (t2, 2t) t 
[0, 2] is an arbitrary point on parabola y2 = 4x. Q is foot of perpendicular from focus S on the tangent at P, then maximum area of 
PQS is-
If P (t2, 2t) t [0, 2] is an arbitrary point on parabola y2 = 4x. Q is foot of perpendicular from focus S on the tangent at P, then maximum area of PQS is-
maths-General
maths-
The equation of the tangent to the parabola y = (x – 3)2 parallel to the chord joining the points (3, 0) and (4, 1) is-
The equation of the tangent to the parabola y = (x – 3)2 parallel to the chord joining the points (3, 0) and (4, 1) is-
maths-General
maths-
If a 
0 and the line 2bx + 3cy + 4d = 0 passes through the points of intersection of the parabolas y2 = 4ax and x2 = 4ay, then
If a 0 and the line 2bx + 3cy + 4d = 0 passes through the points of intersection of the parabolas y2 = 4ax and x2 = 4ay, then
maths-General
maths-
The P be the family of parabolas y = x2 + px + q (q ≠ 0) whose graphs cut the axes in three points. The family of circles through these three points have a common point
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maths-General
Maths-
Consider the two curves C1 : y2 = 4xC2 : x2 + y2 – 6x + 1 = 0Then,
Consider the two curves C1 : y2 = 4xC2 : x2 + y2 – 6x + 1 = 0Then,
Maths-General
