A ball is dropped from a high rise platform at t = 0 starting from rest. After 6 seconds another ball is thrown downwards from the same platform with - Physics MCQ Physics | ExamTest.live

mediumMCQPhysicsPhysics

1 mark

A ball is dropped from a high rise platform at t = 0 starting from rest. After 6 seconds another ball is thrown downwards from the same platform with a speed v . The two balls meet at t = 18 s . What is the value of v ? (Take g = 10 m/s^{2})

A $60 m/s$
B $75 m/s$
C $55 m/s$
D $40 m/s$

Solution & Step-by-step Explanation

Displacement of the first ball in 18 s : s_{1} = \frac{1}{2} g (18)^{2} = \frac{1}{2} (10) (324) = 1620 m The second ball is thrown at t = 6 s and meets at t = 18 s . Time of travel for second ball t_{2} = 18 - 6 = 12 s . Displacement of second ball s_{2} : s_{2} = v t_{2} + \frac{1}{2} g t_{2}^{2} Since they meet, s_{2} = s_{1} = 1620 m : 1620 = v (12) + \frac{1}{2} (10) (12)^{2} 1620 = 12 v + 5 (144) 1620 = 12 v + 720 900 = 12 v ⟹ v = 75 m/s

Practice this question

Try it yourself before checking the explanation above.

A ball is dropped from a high rise platform at t = 0 starting from rest. After 6 seconds another ball is thrown downwards from the same platform with a speed v . The two balls meet at t = 18 s . What is the value of v ? (Take g = 10 m/s^{2})

60 m/s

75 m/s

55 m/s

40 m/s

Share This Question

Mechanics Kinematics Free Fall

Related Questions

mediumMCQ

Consider a water tank as shown in the figure. It has one wall at x = L and is very wide in the z direction. When filled with a liquid of surface tension S and density ρ , the liquid surface makes an angle θ_0 ( θ_0 1 ) with the x -axis at x = L . If y(x) is the height of the surface, then the equation for y(x) is:(Take θ(x) ≈ θ(x) ≈ θ(x) = dy/dx and g as acceleration due to gravity) ![image](https://pub-7faa453bd1ec4bf0a04cc031c6f058de.r2.dev/images/e48999a7-2b29-4d5c-be16-ae2fd5fbcea5.png)

mediumMCQ

A microscope has an objective of focal length 2 cm , eyepiece of focal length 4 cm and the tube length of 40 cm . If the distance of distinct vision of eye is 25 cm , the magnification in the microscope is:

mediumMCQ

An electron (mass 9 × 10^-31 kg and charge 1.6 × 10^-19 C ) moving with speed c/100 ( c = speed of light) is injected into a magnetic field B of magnitude 9 × 10^-4 T perpendicular to its direction of motion. We wish to apply a uniform electric field E together with the magnetic field so that the electron does not deflect from its path. Then (speed of light c = 3 × 10^8 ms^-1 ):

mediumMCQ

There are two inclined surfaces of equal length ( L ) and same angle of inclination 45^ with the horizontal. One of them is rough and the other is perfectly smooth. A given body takes 2 times as much time to slide down on rough surface than on the smooth surface. The coefficient of kinetic friction ( μ_k ) between the object and the rough surface is close to:

mediumMCQ

The kinetic energies of two similar cars A and B are 100 J and 225 J respectively. On applying breaks, car A stops after 1000 m and car B stops after 1500 m . If F_A and F_B are the forces applied by the breaks on cars A and B, respectively, then the ratio F_A/F_B is:

mediumMCQ

The current passing through the battery in the given circuit is: ![image](https://pub-7faa453bd1ec4bf0a04cc031c6f058de.r2.dev/images/5a163a0c-22d0-4a96-bcd2-b569518db0a4.png)

Ready for a Full Test?

Practice with timed mock tests and track your performance across Physics.

Browse Tests Leaderboard

A ball is dropped from a high rise platform at $t = 0$ starting from rest. After $6 seconds$ another ball is thrown downwards from the same platform with a speed $v$ . The two balls meet at $t = 18 s$ . What is the value of $v$ ? (Take $g = 10 m/s^{2}$ )

Solution & Step-by-step Explanation

Practice this question

Share This Question

Related Questions

Ready for a Full Test?

Discussion

A ball is dropped from a high rise platform at t=0 starting from rest. After 6 seconds another ball is thrown downwards from the same platform with a speed v. The two balls meet at t=18 s. What is the value of v? (Take g=10 m/s2)

Solution & Step-by-step Explanation

Practice this question

Share This Question

Related Questions

Ready for a Full Test?

Discussion

A ball is dropped from a high rise platform at $t = 0$ starting from rest. After $6 seconds$ another ball is thrown downwards from the same platform with a speed $v$ . The two balls meet at $t = 18 s$ . What is the value of $v$ ? (Take $g = 10 m/s^{2}$ )