Search results

1. Momentum (Conceptual) Question

Suppose there is a cannon that shoots a cannon ball at a certain angle above the horizontal (a projectile). Since momentum is conserved in both directions, the cannon should posses a velocity now in the y (or z-axis if you would like to call it) and in the x axis. 1) However, what does it...
2. Power dissipated in a resistor

Think about first combining resistors. Reply back to show your work for that. From there, it should be simple to get the I in the 6ohm resistor.
3. How much work does the earth do? help!

a) Work = Fd when they're in the same direction. So the force on the mass is mg (.105 x 9.8), and the distance it moves down is .06 meters. So solve for Fd (they're in the same direction so the answer is positive). b) We'll write that the spring and earth do work on the mass: so -1/2kx^2 + mgh...
4. Physics Kinematics of a swimmer

Break the motion into an x and y components. We'll say the swimmer undergoes a displacement of 480 meters in the +x direction. The time it takes for this to happen is 6 minutes and 40 seconds (400 seconds). So 480/400 = 1.2 m/s. Remember, the key to solving this is thinking about the problem...

So the soccer ball hits the crossbar (assuming it hits at 2.5 meters high). What does that mean? Do what fss said and break the motion into components, x and y. 2.5 is the positive y displacement. So we have 2.5 = vy (t) + 1/2a(t^2). So what is vy? and what is a? If you have a question...
6. Finding acceleration (Simple)

Average Acceleration = Change in velocity / time. Let's first convert 1000km/hour to m/s. The answer to that is 277.7 meters/second. Now, we'll define direction (east is positive, west negative). So after it makes the turn, it's velocity is +277.7 m/s. Before it makes the turn, it's velocity...
7. Normal Force!

Start with the free body diagram. Label your normal force and see if you can equate it to something. If you're stuck, let us know.
8. Finding Speed Using Conservation of Energy

3.85 should be correct...Do you know what your source says the answer is?
9. Finding the speed of an arrow

In order to use the range formula, we would have to draw in the other half of the parabola so that the arrow ends up at the same height as it started (ie a vertical displacement of zero). This means we have the 66 m which is the half parabola it travels, plus the 66 m of the other half parabola...
10. Motion Near Earth's Surface - grade 11 physics

In the original, you just did the math incorrectly: It's the F(up) - mg = ma. So F = ma + mg. In your coursebook, could you state the problem that it's listed for?
11. Finding the speed of an arrow

No, in my older post, i forgot to include the fact that the arrow was released parallel to the ground (ie no initial y velocity). I will re-write the corrected solution right here. If he releases the arrow parallel to the ground it makes half a parabola in its trajectory. Now, draw the other...
12. Finding the speed of an arrow

sorry, if he releases the arrow parallel to the ground it makes half a parabola in its trajectory. Now, draw the other half. You'll see that the x distance of this parabola now is 66 x2. Then, you can follow my last post. If you'd like to stick with this, you'd have to solve for the x...
13. Finding the speed of an arrow

Use the range equation for this, since it returns to the same initial height released (theoretically). V^2 Sin (2 theta)/g = Range. We know that the angle of 3 degrees it makes with the ground is the same three degrees it was released at above the horizontal. Hence, we have v^2 (sin 6)/9.8 =...
14. Athlete jumps at angle with distance find speed

Since you have to assume that his y displacement is zero by the time he lands, you could use the range equation for this which is (v^2)sin(2x)/g. You know the range is 7.77 and you know x, which is the angle. So solve for v. For the second case, all is being kept constant, except for...
15. Conceptual Question About Vertical Spring System

Thanks for your help; that's brilliant. However, wouldn't the stretch be the same even if it was lowered? For the first equation: x = mg/k. For the one slowly lowered, since the forces are balanced once it reaches equilibrium, shouldn't the stretch be x = mg/k also?
16. Conceptual Question About Vertical Spring System

Suppose there is a spring with a mass m attached to it, and it is released from rest. It will oscillate, starting from a certain point y0, going back to equilibrium and then down to let's say y2. Let's say in the first case, I call y1 my x = 0 point for the spring. When it passes equilibrium...