Search & Filtering
A man lifts a heavy box that weighs 121 N into the air. If the net force on the box is 6.0 N upward, what is the magnitude of the lifting force that the man puts on the box?
Each of 39 of my friends has either a dog, a cat or a rabbit. Each of 24 of them has a dog, each of 17 has a cat and each of 16 has a rabbit. The number having both a dog and a cat is 1 more than the number having both a cat and a rabbit. There are 9 who have both a dog and a rabbit while 2 of them have all the three. How many of my friends have both a rabbit and a cat?
The speed c of ocean wave is proportional to the acceleration due to gravity g, wavelengthλ, and densityρof the wave such that c =kgxλyρz, where k is a dimensionless constant. What is the correct equation for the speed of the ocean?
Assume that the rate of accretion of material to a spherical planet is given by
dV/dt = A+BV
Where V is volume, t is time and A and B are constants. Neglecting compression of the material that accretes with a density p:
(a) Write an expression for the radius of the planet with time if B=0.
(b) Write an expression for the radius of the planet with time if A=0 and at time t=0 the volume of the planet is V0.
(c) For case (b) write an expression for the average temperature of the planet with time if the specific heat of the material forming the planet is CP.
1.The right end of a rod with length L and total charge Q is at a distance L to the surface of a
spherical object with diameter L and total charge Q also, as shown in the figure. The axis of
the rod and the center of the spherical object are collinear. Determine the magnitude of the force exerted by the two objects on each other, and whether
the force is attractive or repulsive for the following cases:
A. Both the rod and the sphere are insulators, the charge Q is uniformly distributed on
the rod and the surface of the sphere.
B. The rod is an insulator while the sphere is a conductor. The charge Q is uniformly
distributed on the rod.(Use method of images)
This question concerns polarisation.
a) Explain what is meant by polarisation of a wave. This should include a mention of which types of wave can, and which cannot, be polarised (3 marks)
b) Explain why the two sheets of Polaroid will both allow light through in one orientation, but when one is rotated by 90o light is no longer transmitted.
This question concerns the images formed by lenses.
a) Make a scale drawing to show how an image is formed by a diverging lens. The lens has a focal length of 10 cm, and the object is 5 cm from the centre of the lens. The object is 2 cm tall. Hint: the ray diagram will be much easier to draw if you use squared paper. (4 marks)
b) Is the image real or virtual? Give a reason for your answer (2 marks)
c) Use the lens formula, with the sign convention ‘real is positive’ and the given object distance and focal length to confirm that this image is in the correct place (2 marks)
d) Calculate the magnification, and compare it to the magnification measured from your drawing (2 marks)
e) What is the power of this lens? (2 marks)
f) If you add a second lens to this, with a power of + 10 dioptres, what is the total power? (2 marks)
What is energy of H atom.
Spin of paticles explain.
Explain rotational energy.
