Explanation:

Rate of change of Momentum = Force

use the conservation of energy, all the kinetic energy that it has at the bottom is equal to the potential energy it will have at the top. Quick and dirty assumption that g = 10 m/s²

mv²/2 = mgh

v²/2 = gh

h = v²/2g

h = (20 m/s)² / (2 × 10 m/s²)

h = (400 m²/s²) / (20 m/s²)

h = (400/20) (m² × s²) / (m × s²)

h = 20 m

When a projectile is rising up, due to gravity the ball's vertical component of velocity continuously start decreasing because ball is travelling against the gravity . Now, at the highest point of a projectile path , the velocity in the vertical direction becomes zero.

Explanation:

It is a straight line path hence the displacement = distance. Particle may not reverse the direction of motion due to constant acceleration. Average velocity is equal to average speed due to linear motion. Because object is accelerating, i.e. changing velocity with time, the average velocity is not equal to instantaneous velocity.

Vi = 0;    a = 9.8 m/s2;    t = 3s

From s = v₁t + (1/2)at²

s = (1/2) * 9.8 * 3² = 44.1 m.

Explanation:

For an object moving in uniform circular motion, the direction of the instantaneous acceleration vector is directed radially inward, perpendicular to the tangential velocity.

Explanation:

Retarded motion is deceleration which implies negative acceleration, thus the slope of the velocity time graph for retarded motion is negative.

For motion with uniform velocity, magnitude of displacement = distance

Explanation:

When the particle is in motion for some time, the speed and distance covered cannot be zero because the particle is moving. However, the displacement can be zero because the particle can come back to its initial position. In this case, the final position of the particle coincides with its initial position such that displacement, which is a distance with direction, becomes zero.

Explanation:

From Newton'a second law, force $F=ma$

$⟹$  F / a ​= m

Thus ratio of force and acceleration is equal to mass of the body.

horizontal initial velocity of Ball will be same as that of Bus but if Ball lands in front of her and She faces engine means Bus has traveled more distance than the Ball. so Bus must be accelerating otherwise if Bus was with constant velocity then Ball will come back to the boy, or moving backward with de-acceleration.

The acceleration of a moving object can be found from Slope of Velocity time graph

If two particles start from rest simultaneously and are equally accelerated, they will have the same acceleration and will move together with the same velocity at all times.

Therefore, the relative velocity of one with respect to the other will be:

Explanation:

Thus, the particle will be back at it's initial position after 2 minutes. 
Thus, $|displacement|=0\; so\; the\; ratio\; will\; Also\; Zero$

In completing 1 revolution, distance covered  $=2\pi R$ and displacement = 0,

for half Revolution:
distance covered  $=\pi R$
and displacement = 2R

The formula for conversion is,

km/h = (18/5) x m/s.

Therefore,

15 m/s = 15 x (18/5)

= 54 km/h.

Explanation:

Explanation:

• Newton's first law states that, if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force. This postulate is known as the law of inertia.
• Hence a force is not required to keep the particle moving with uniform speed

The rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts.

Explanation:

Explanation:

If the speed of a straight line moving object changes, its speed is called Changed.

• Uniform speed:

  • An object is said to be in uniform speed when the object covers equal distance in equal time intervals.

• Variable speed:

  • ​An object is said to be in variable speed when the object covers a different distance at equal intervals of times.

• Average speed:

  • ​Average speed is defined as the uniform speed which is given by the ratio of total distance traveled by an object to the total time taken by the object.

• Instantaneous speed:

  • When an object is moving with variable speed, then the speed of that object at any instant of time is known as instantaneous speed.

Explanation:

When distance is proportional to time, the ratio of distance and time remains constant. This means that in equal time intervals, the particle is travelling equal distances. So clearly the speed of the particle remains constant.

The acceleration is the rate of change of velocity. Any change in velocity – with magnitude or direction – will result in acceleration.
Therefore, in the given case, there exists no acceleration or speed variation. Also, the speed will not be zero.
The acceleration of the particle in motion will be zero during a uniform velocity.

Explanation:

When displacement is zero, particle may be at rest, therefore, distance travelled = 0.

Again, when displacement is zero, final position coincides with the initial position, distance travelled is not zero.

Explanation:

• As the Body reached to its initial Position its mean Displacement is zero.
• For Distance = Circumference = n (2 π r) 

Here: r = 3R 

and :-  n= 2

Distance = 2 ( 2 π (3R)

Distance = 12 π R

Explanation:

Explanation:

• The direction of acceleration is determined by the general principle that if an object is slowing down, the acceleration is in the opposite direction of the motion.
• Hence, with negative acceleration, the velocity of a body decreases.
• The negative sign of acceleration shows that the velocity of the body is decreasing per unit of time.

Explanation:

• Time rate of change of linear momentum represents force and
• time rate of change of angular momentum represents torque.

Derivation:

Initial momentum P¹ = m × u

Final momentum P² = m × v

According to question,

dP/dt (rate of change of momentum) = (P² - P¹)/t

= m ( v - u ) / t

= m a

= Force

So, rate change of momentum is equal to Force.

Explanation:

u(initial velocity) = 19.6 m/s

at highest point v(final velocity)=0

using v=u + at

0 = 19.6 - 9.8 * t

t=19.6/9.8= 2s (time  to reach max height)

Explanation:

Concept is change in velocity = 4 - 3 = 1 

And total time = 0.5

Acceleration = 1/0.5 = 2

Explanation:

Suppose the acceleration is $a$ then using the second equation of motion, s = ut + 1/2​ at^2

and putting $t=2sec$ and $u=10m/s$ 

we get $20=10\times 2+a\times 2$

or $a=0$ that is $uniform$ motion

Explanation:

According to Newton's third law, if the table exerts $40N$ force on the block, the block will also apply same force on the table. As $9.8N<40N$, the net force is in upward direction and thus, the block has an upward acceleration

NOTE: On This concept Similar MCQs were in NMDCAT 2021 but this is not Exact statement but the concept is same.

According to the law of conservation of momentum, the momentum of a system remains constant if no external force acts on it.

1) When the shot is fired from a cannon and explodes in mid-air, no external force acts on it, and therefore, the linear momentum is conserved.

2) When the cannon explodes, the chemical potential energy stored in the explosives gets converted to kinetic energy due to the velocity acquired.

Therefore, when a shot is fired from a cannon and explodes in mid-air, the momentum will remain constant but kinetic energy will increase.

Explanation

Explanation:

Initial linear momentum of the system: P_i =mv=50 x 10 =500 kg m/sec
Final Momentum of The System: P_f = (M + m)V

P= (50+20)V
P= 70V
According to Law of Conservation of Momentum:
Final Momentum = Initial Momentum
70V = 500
V= 500/70 = 7.1 km/h