JEE Mains Morning Question 11th Jan Paper 2019 Physics Part 1 Download all the papers for 2019 Exam

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Q-1 A body is projected at with a velocity at an angle of with the horizontal. The radius of curvature of its trajectory at t=1s is R. Neglecting air resistance and taking acceleration due to gravity , the value of R is:

Options:-

1. 2.5 m

2. 10.3 m

3. 2.8 m

4. 5.1 m

Answer: 3

Explanation:-

Image of projected velocity harizontal resistance

Image of Projected Velocity Harizontal Resistance

Image of projected velocity harizontal resistance

Path followed by a projectile is parabolic is nature.

Velocity after t=1 sec

Q-2 A particle is moving along a circular path with a constant speed of . What is the magnitude of the change in velocity of the particle, when it moves through an angle of around the centre of the circle?

Options:-

1. Zero

2. 10 m/s

3.

4.

Answer: 2

Explanation:-

Image of particle circle path with a constant speed

Image of Particle Circle Path with a Constant Speed

Image of particle circle path with a constant speed

Relative velocity of a body, A with respected body B when the to bodies moving at an angle θ.

Where in

Since,

Q-3 A hydrogen atom, initially in the ground state is excited by absorbing a photon of wavelength . The radius of the atom in the excited state, in terms of Bohr radius , will be:

Options:-

1.

2.

3.

4.

Answer: 4

Explanation:-

New radius will be

Q-4 A liquid of density is coming out of a hose pipe of radius a with horizontal speed V and hits a mesh. 50% of the liquid passes through the mesh unaffected. 25% looses all of its momentum and 25% comes back with the same speed. The resultant pressure on the mesh will be:

Options:-

1.

2.

3.

4.

Answer: 2

Explanation:-

Momentum per second carried by liquid per second is

Mess per unit time Av

Net force due to reflected liquid=

Net force due to stopped liquid=

Pressure =

Pressure =

Pressure =

Pressure =

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