1
JEE Main 2019 (Online) 11th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A liquid of density $$\rho $$ is coming out of a hose pipe of radius a with horizontal speed $$\upsilon $$ 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 :
A
$${3 \over 4}\rho {v^2}$$
B
$${1 \over 4}\rho {v^2}$$
C
$${1 \over 2}\rho {v^2}$$
D
$$\rho {v^2}$$
2
JEE Main 2019 (Online) 11th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A satellite is revolving in a circular orbit at a height h form the earth surface, such that h < < R where R is the earth. Assuming that the effect of earth's atmosphere can be neglected the minimum increase in the speed required so that the satellite could escape from the gravitational field of earth is :
A
$$\sqrt {gR} \left( {\sqrt 2 - 1} \right)$$
B
$$\sqrt {2gR} $$
C
$$\sqrt {gR} $$
D
$${{\sqrt {gR} } \over 2}$$
3
JEE Main 2019 (Online) 11th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Ice at –20oC is added to 50 g of water at 40oC. When the temperature of the mixture reaches 0oC, it is found that 20 g of ice is still unmelted. The amount of ice added to the water was close to (Specific heat of water = 4.2J/g/oC Specific heat of Ice = 2.1J/g/oC Heat of fusion of water at 0oC= 334J/g)
A
100 g
B
60 g
C
50 g
D
40 g
4
JEE Main 2019 (Online) 11th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
If the de Broglie wavelength of an electron is equal to the 10–3 times the wavelength of a photon of frequency 6 $$ \times $$ 1014 Hz, then the speed of electron is equal to : (Speed of light = 3 $$ \times $$ 108 m/s, Planck's constant = 6.63 $$ \times $$ 10–34 J.s, Mass of electron = 9.1 $$ \times $$ 10–31 kg)
A
1.7 $$ \times $$ 106 m/s
B
1.45 $$ \times $$ 106 m/s
C
1.1 $$ \times $$ 106 m/s
D
1.8 $$ \times $$ 106 m/s

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