1
JEE Main 2019 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Four particles A, B, C and D with masses mA = m, mB = 2m, mC = 3m and mD = 4m are at the corners of a square. They have accelerations of equal magnitude with directions as shown. The acceleration of the centre of mass of the particles is : JEE Main 2019 (Online) 8th April Morning Slot Physics - Center of Mass and Collision Question 84 English
A
$${a \over 5}\left( {\mathop i\limits^ \wedge + \mathop j\limits^ \wedge } \right)$$
B
$${a \over 5}\left( {\mathop i\limits^ \wedge - \mathop j\limits^ \wedge } \right)$$
C
$${a }\left( {\mathop i\limits^ \wedge + \mathop j\limits^ \wedge } \right)$$
D
Zero
2
JEE Main 2019 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Two identical beakers A and B contain equal volumes of two different liquids at 60°C each and left to cool down. Liquid in A has density of 8 × 102 kg/m3 and specific heat of 2000 J kg–1 K–1 while liquid in B has density of 103 kg m–3 and specific heat of 4000 J kg–1 K–1. Which of the following best describes their temperature versus time graph schematically? (assume the emissivity of both the beakers to be the same)
A
JEE Main 2019 (Online) 8th April Morning Slot Physics - Heat and Thermodynamics Question 270 English Option 1
B
JEE Main 2019 (Online) 8th April Morning Slot Physics - Heat and Thermodynamics Question 270 English Option 2
C
JEE Main 2019 (Online) 8th April Morning Slot Physics - Heat and Thermodynamics Question 270 English Option 3
D
JEE Main 2019 (Online) 8th April Morning Slot Physics - Heat and Thermodynamics Question 270 English Option 4
3
JEE Main 2019 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Voltage rating of a parallel plate capacitor is 500V. Its dielectric can withstand a maximum electric field of 106 V/m. The plate area is 10–4 m2. What is the dielectric constant is the capacitance is 15 pF? (given $$\varepsilon $$0 = 8.86 × 10–12 C2/Nm2)
A
8.5
B
4.5
C
3.8
D
6.2
4
JEE Main 2019 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A boy's catapult is made of rubber cord which is 42 cm long, with 6 mm diameter of cross-section and of negligible mass. The boy keeps a stone weighing 0.02kg on it and stretches the cord by 20 cm by applying a constant force. When released, the stone flies off with a velocity of 20 ms–1. Neglect the change in the area of cross-section of the cord while stretched. The Young's modulus of rubber is closest to:
A
104 Nm–2
B
106 Nm–2
C
108 Nm–2
D
103 Nm–2
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