# Search results

1. ### Binomial Probability problem.

Homework Statement 10% of engines manufactured on an assembly line are defective. If engines are randomly selected one at a time and tested, what is the probability that the first defective engine will be found between the 5th trial and the 25th trial, inclusive? Homework Equations...
2. ### Derivative of (1+e^-x)^-1

Homework Statement Find the derivative of (1+e^-x)^-1 Homework Equations The Attempt at a Solution I can't seem to get anywhere with this. Should I be looking for a property of something like the cosh function to apply to this? Thanks
3. ### Simple Probability Proof

Homework Statement Prove the following: P(A∩B) ≤ P(A) ≤ P(AUB) Homework Equations The Attempt at a Solution I first attempt to show that P(A) is a subset of P(AUB) which therefore means it is ≤ P(AUB): P(AUB)=P(A)+P(B)-P(A∩B), thus P(A) is a subset of P(AUB)...I think that...
4. ### Question about a derivative and double angle formula

If I am supposed to find the derivative of the equation sin^2(x) the derivative is 2sinxcosx, by the double angle formula can I say that the derivative is therefore sin2x or can I not do this because I am simply finding the derivative.
5. ### Reflection of light

Homework Statement A person stands 3.6m in front of a wall that is covered floor to ceiling with a plane mirror. His eyes are 1.8m above the floor. He holds a flashlight between his feet and manages to point it at the mirror. At what angel of incidence must the light strike the mirror so...
6. ### Battery problem

Homework Statement A schematic diagram incorporates a 12V battery in series with a 3.0 ohm resistor. The current then flows through 12 ohm and 4.0 ohm resistors in parallel with each other. a) calculate the current through and voltage across each resistor. 3.0ohm 4.0 ohm 12ohm 24ohm 4.8 ohm...
7. ### Diving Board Question

Im not sure if I have to add both weights and if so I dont know if I am adding them to the right spots. Q) A 596N diver is standing at the edge of a diving board, 1.9m from the fulcrum of a 114N diving board. The fulcrum is located 2.1m from where it is bolted at the opposite end Find the...
8. ### One more impulse problem Hopefully

a good bunter pulls the bat back right as contact is made with the ball. Why is this so? 1 This action decreases the impulse of the bat on the ball 2 This action increases the impulse of the bat on the ball 3 This action increases the average force of the bat on the ball 4 This action...
9. ### Impulse question

Jumping onto sand vs. jumping into water results in which of the following as each substance brings you to a halt? a) The sand exerts a greater impulse than the water b) The water exerts a greater impulse than the sand c) The sand and water exert the same impulse, but the sand exerts a...
10. ### Force Question

A hockey goalie m=85kg stands in front of the net. A player hits the 0.15kg puck towards the goalie with a velocity of +59m/s. The goalie catches the puck with his glove in a time of 0.0021seconds. (assume all collisions are linear) A) what is the average force of the puck on the goalie? I...
11. ### A couple of questions

I have no idea how to do this first one 1. Youre coasting with a friend on a sled, going a constant velocity, having a momentum of +120kg m/s when suddenly your friend bails off the sled. Assuming there are no net external forces acting on the system which of the following gives a correct...
12. ### Mechanical Energy Q

So I have a quick question that I got in my physics class and I'm not to informed on Mechanical energy so if you could help me out that would be great: Which of following is/are true regarding the principle of mechanical energy? I. An object moves uphill with a decreasing speed II. An...