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That is not the answer. The change in momentum, is 2mvcos22.5.

I got it as 2mvcos45.
In the answer, its given that the direction of impulse is along the angle bisector. I did not understand that part. So someone explain.

A batsman deflects a ball coming at him with a velocity of 54 km/hr by an angle of 45^o, without changing the speed of the ball. What is the magnitude and direction of the impulse imparted to the ball, if the mass of the ball is 0.15kg?

hey.. dude can you give simpler explanations, with examples?

Your answers are perfect for both.

biki is wrong. In both the cases, friction will act upwards. This is because of the following:

1. When the disk is rolling down, we all know that friction is an opposing force, so the direction of frictional force is opposite to the motion of the disk, ie, it is upwards.

2. Here's the catch, when the disk is going up, Friction helps the disk in the motion, so the direction of friction is taken as upward.
Just think, if there were no friction, would you be able to roll a ball up an inclined plane? No! It is friction which helps the upward motion (Rotation+translation) of any object.

Therefore, in general, friction aids upward motion. You will come across this concept quite often when you solve inclined plane problems.

Cheers!

Are you sure the sum is right? Anyway, this is how you proceed :

By prime factorization, you get 45321 = 15107 x 3 (Let me know if there are any prime factors of 15107 itself)

Now, abcde can take any of these values each.. that is the solution can be:

15107x3x1x1x1, 15107x1x1x1x3, etc etc...

So this is a permutation problem now. The number of ways to arrange the 2 numbers 15107 and 3 among the five variables, abcde.
This is 5!/3! = 20 ways.

But the solution can also be like (15107x3), 1, 1, 1, 1.

So total no of ways are 20+5! = 20+120 = 140 ways, ie, 140 positive integral solutions.

if u are just in class XI, then chill. There's no need for you to worry about calculus now.

Experts please!! Help me...

Experts!!!

See, if the function is to have a maximum or a minimum, at that point, the slope of the tangent will be zero. Thats why we equate it to 0. I know its difficult to explain without a graph. I'll try to draw a graph and explain.

It is quite simple : Assuming you know differentiation, here's how you proceed :

1. Say you are given some function (which people nowadays call it by a wierd name, generally as f(x)) f(x), first differentiate it, and find f'(x).

2. Equate f'(x) to zero, and find the unknown variable. In our case, since the function is dependent on x, we will find a value for x.

3. Once you get the value of the variable, what you do is, differentiate f'(x) again, ie, find f''(x). Now, put the value of the x that you found in f''(x).

4. If f''(x) is positive, then that value of x gives the minimum value of the function. If it is negative, then it is the maximum.

let me do this sum for you :

h = 2t-5t^2.

differentiating wrt to t, we get : f'(t) = 2 - 10t.

equating it to zero, we get 10t = 2, or t = 0.2 seconds.

Differentiating again wrt to t, we get the second derivative as -10.

Since the second derivative is 0, the value of t that we got is the maximum.

Thus, t = 0.2 seconds.

Maximum height can be found by putting this value of t in the original function.

Hope it helped.

Dude, don't crap... its quite obvious that you edited the link. Don't think we guys are fools over here. My computer doesn't have any spyware. Go get a life.

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Why doesn't any expert answer this????

I think he should try for production engg from nit srinagar