Total time taken to reach the top and then return to the ground: t = 2u/g

u=20 m/sec, and g= 10

t= 2(20)/10=4 Sec

Explanation:

Explanation:

Explanation:

Explanation:

• Acceleration is the rate of change of velocity with respect to time.
• 
  Acceleration=Velocity/Time 
• Whenever a body accelerated its velocity definitely changes.
• Acceleration occurs anytime an object's speed increases or decreases, or it changes direction.
• If the speed of the body is increasing, the body has positive acceleration.
• If the speed of the body is decreasing, the body has negative acceleration.
• Therefore when the body is accelerated Its speed may or may not change.

Explanation: 

By using the equation: v = u +at we can get the answer.

At highest point, velocity, v = 0 m/s and acceleration, a = -g = -10 m/s^2.

Initially the velocity, u = 100 m/s.

Therefore, 0 = 100 - 10t

=> t = (-100)/(-10) =10 seconds.

Explanation: 

Because there is no acceleration or retardation along horizontal direction, hence horizontal
component of velocity remains same

Explanation:

In the absence of air resistance, the projectile moves with constant horizontal velocity
because acceleration due to gravity is totally vertical and its horizontal component is zero

Step 1: Convert Km/h to m/sec

Explanation:

The vertical component goes on decreasing and eventually becomes zero.

Explanation:

Let the total time be 2t. Then the distance covered during the first half time t is
S₁=v₁t,
and that during the second half time is
S₂= v₂t

Explanation:

Using the equation for the distance travelled in the nth second,

we have, for the first second,

The distance travelled in the second second is

Explanation:

Using the equation for the distance travelled in the nth second,

Explanation:

a body can have a constant speed and still be accelerating. Acceleration can be either due to change in speed or due to direction of motion or both. Consider an example of a uniform circular motion. In a circular motion, the body moves with a constant speed but we still say that it is accelerating due to the change in direction

Explanation:

Explanation: 

As Earth is Revolving around the sun, The shortest distance between both at Each Point is "r" 

The displacement of the Sun with respect to the Earth is the distance between the two objects. Since the Earth orbits the Sun at an average distance of r, the displacement is r. This is the typical way it is expressed, assuming a simplified model of the Earth's orbit as circular.

Explanation: 

When a body reach to its initial Position, its Displacement become Zero, so Similarly incase of Circular Motion a body Must reach to its initial Position, so its Displacement Must be zero.

Explanation:

Let m be the mass of the two identical balls. 

• u₁ = velocity before the collision of ball 1
• u₂ = 0 = velocity of second ball that is at rest
• v₁ and v₂ are the velocities of the balls after the collision.

From the conservation of momentum,

mu₁ + mu₂ = mv₁ + mv₂

⇒ mu1 = mv1 + mv2 ⇒ u₁ = v₁ + v₂

In an elastic collision, the kinetic energy of the system before and after collision remains same.

After Simplification we left with: 

2V1V2=0

• The second ball moves, hence velocity v₂ cannot be zero.
• Thus, the velocity of the first ball v₁ is zero i.e. it comes to rest after collision.

Explanation: 

• Since the velocities are the same, the kinetic energy before and after remains the same.
• Thus, the change in kinetic energy of the ball is 0%

Explanation: 

as we know: p=mV=kg . m/sec

Explanation: 

Newton's third law of motion : For every action there is always an equal and opposite reaction acting on the other body.

Explanation:

All mentioned quantities except force are kinematic quantities. Force is a kinetic quantity.           Force = m x a. Hence, the mass of the body has an effect on force calculation.

Explanation:

The formula for horizontal range is h = (v sinθ)²/2g. This will be maximum when sin θ = 1, which implies that θ = 90°. Hence the correct answer is when θ = 90°

Explanation: 

Time to reach max height =u/g

Total time of flight =2u/g

Given:

u = 9.8 m/s

Time of flight = u/g=9.8/9.8=1 sec

Total time of flight=2 x 1 = 2 sec

Explanation:

Here g=10, u=15 m/s, θ with the horizontal is 30 °

Explanation:

Given, $\theta =30$°

$KE=K$. We know that,

As we Know that K:E at Highest Point during Projectile motion is:

EXPLANATION:

• Newton’s First law of motion says about the state of rest or uniform motion and is valid on only Inertial Frame.
• Thus newton’s laws are not valid in a non-inertial frame

EXPLANATION:

• While swimming, a person pushes water with his hands in the backward direction (action) and water, in turn, pushes him forward due to the force of reaction.
• Hence the forward movement in swimming takes place because of the third law of motion.

EXPLANATION:

Given that: Mass of the ball (m) = 2 kg

Initial velocity of ball (V₁) = 0 and Final velocity of ball (V₂) = 20 m/s

Impulse (J) imparted to the ball = P₂ – P₁ = 2 × 20 – 2 × 0 = 40 kg m/s

Newton’s Second Law:

• The rate of change of linear momentum of a body is directly proportional to the external force applied on the body and this change takes place always in the direction of the applied force.
• If a body of mass m moves with velocity v then its linear momentum can be given by p=mv and if force F is applied on a body, then

P=mv

Where F = Force, m = mass and a = acceleration

From above it is clear that Newton’s second law of motion explains about change in momentum.

EXPLANATION:

• Momentum is the total quantity of motion contained in the same body. Therefore option 3 is correct.
• The pressure is the perpendicular force applied to the surface of objects per unit area. Therefore option 1 is incorrect.
• Force is defined as pushing or pulling of an object, due to which the motion of the body will be changed. It is equal to the product of mass and acceleration. Therefore option 2 is incorrect.
• The inherent property of all the bodies by virtue of which they cannot change their state of rest or uniform motion along a straight line by their own is called inertia

When particle moves the first half of a distance at a speed of v1 and second half of the distance at speed v2

Explanation:

According to equation of motion, distance covered in $n$th sec

a/2 is constant in all So it will Cancel out

Explanation:

in Free fall motion the time of flight is always independent of mass

Explanation:

A body acted upon by a certain force produces acceleration i.e. it undergoes change in it's velocity and momentum and kinetic energy of a moving body depends on the velocity of the body

EXPLANATION:

• When a bus suddenly starts moving, the passengers fall backward due to the law of inertia of rest or 1st law of Newton.
• Because the body was in the state of rest and when the bus suddenly starts moving the lower body tends to be in motion, but the upper body still remains in a state of rest due to which it feels a jerk and falls backward. Hence option 1 is correct.

Laws of Motion given by Newton are as follows:

EXPLANATION:

• The heavier the object is harder to move it or the greater the amount of force required to move it hence higher the inertia.
• Since higher mass has higher inertia. In all the above 4 options, a cricket ball has maximum mass so it will have maximum inertia. Hence option 4 is correct.

EXPLANATION:

Given - Acceleration (a) = 2 m/s², Final velocity (v) = 30 m/s and Initial velocity (u) = 20 m/s

Displacement = s

We know,

⇒ v² - u² = 2as (Equation of Motion)

⇒ s = (v²- u²)/ (2 x a)

⇒ s = (30²-20²) / (2 x 2)

⇒ s = 500 /4

⇒ s = 125 m

EXPLANATION:

• When we beat the blanket then the blanket material moves with the stick in the forward direction.
• But the dust particles were at rest, so it will remain at rest at their respective position.
• Due to this the dust particles will separate from the blanket and fall down due to the force of gravity.
• Here the dust particle was at rest initially and due to its inertia of rest properties it remains at rest after beating the blanket with the help of a stick and falls down.
• Thus it is based on the First law of motion

Explanation:

If we approximate the acceleration due to gravity as g = 10 m/s2, then the weight of a mass on the surface of Earth is given by Fg = mg = (7.5 kg)
(10 m/s2) = 75 N.

Explanation: 

As we Know Chang in Velocity with respective time is Acceleration, Look at the Question the change is 5 and and time is 1 Sec: so 5 m/sec2

Explanation : 

For a given mass P∝v If the momentum is constant then it's velocity must have constant, Acceleration and Force will remain zero.

Explanation: 

Taking rocket + fuel as system total linear momentum must be conserved since there is no external force. As the exhaust moves out with high speed towards the Earth , the rocket moves with same momentum away from the earth as the net momentum should be zero .

• When a body is moving with a constant velocity, then displacement-time
  graph will be a straight line.

• When a body is moving with a constant acceleration, the displacement-time
  graph is a parabola.

• When a body is moving with a constant retardation, the displacement-time
  graph is a curve which bends downwards.

• When a body is moving with infinite velocity, the time-displacement
  curve is a straight line AB parallel to displacement axis. But such motion of a body is never possible

Explanation:

On a position–time graph, the slope of the line gives speed.
Steeper line means larger slope, so higher speed.
Since P’s line is steeper than Q’s, P moves faster than Q.

Explanation: 

Horizontal v–t line means velocity value is same at all times.
No change in velocity means zero acceleration.
So the body moves with constant velocity.

Why others are wrong:
B) Constant acceleration needs a sloping line, not flat.
C) Decreasing velocity would be a line sloping downwards.
D) At rest would be a horizontal line on the time axis at v = 0.

Explanation: 

As the body A is dropped from rest,

As the body B is given a horizontal velocity at the time of release, it is going to follow the same trajectory as a body on a projectile motion, projected with a velocity having the same horizontal component as the horizontal velocity given to B at H. So the time taken by B from H to Y is same as that from X to H. Now let the vertical component of velocity at X be v then at H,

If n bullets each of mass m and velocity v are fired from a gun then the average force
acting on the gun is mnv

F=ΔP/Δt

F=mv/t
for n bullets we get, mnv/t (put t=1 sec)

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