Homework Help: Force and Acceleration

1. Apr 12, 2005

jpmaster

Hey, i really struggle in Physics, i mean really, its not my best subject, so if you can help me with these questions i would be forever in your debt.

1) Use the braking distance at 20 m/s to calculate the braking force required
(the braking distance being 32 metres, the mass 800KG)

2) During the test the pendulum deforms the crumple zone, the crumple zone is shortened by 0.6 m, what is the average retarding force on the pendulum,
(the mass in 1000kg and the raised hight is 3m, the weight of one kg is 10N)

3) The force between the block and the rim is 800N and the area of the block is 2.0cm squared, calculate the pressure.

4) Before the tyres are changed in a pit stop during the race, the new tyres are wrapped in electric blankets to pre-warm them. calculate the maximum temperature rise of the rubber using this data

Energy supplied by blanket: 540 000 J
Mass of tyre: 12KG
Specific heat capacity of rubber: 1500 J/KG degrees

5) The car accelerates steadily from rest at 20 m/s squared, for 5 seconds, calcualate its speed after 5 seconds.
What is its average speed during this time.

6) The mass of the pendulum is 100KG and it is raised a height of 3m, the weight of 1KG is 10N, how much gravitational potential energy does it gain.?
What is its kinetic energy on impact with the car.

2. Apr 12, 2005

Gokul43201

Staff Emeritus
3. Apr 12, 2005

jpmaster

i wasnt hoping for the answers, only the formulae so i can work it out myself

4. Apr 12, 2005

jpmaster

ARGH, i cant do any of it, please just help me

5. Apr 12, 2005

jpmaster

you can ban me after, but i really do need help, desperately

6. Apr 12, 2005

Gokul43201

Staff Emeritus
If you show some effort (really, any sign that you've thought about these problems), we would be more inclined to help.

7. Apr 12, 2005

Delta

Keywords:

1. Formulae involving energy
2. Formulae for Pressure
3. Specific heat capacity
4. Equations of motion

8. Apr 12, 2005

jpmaster

i would show effort if i knew where to start, but i dont

9. Apr 12, 2005

Gokul43201

Staff Emeritus
Start by reading your text.

I don't mean to be rude - this is really the best advice for the situation you are in. You can not solve problems by just substituting in formulae. You need to learn the physics behind the formulae.

10. Apr 12, 2005

jpmaster

thats the problem, i dont understand anything to do with physics

11. Apr 12, 2005

Gokul43201

Staff Emeritus
What text do you use ?

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