You are helping two friends from our class with a physics problem where a cart is pushed up a ramp. In examining the motion of t
he cart up the ramp, one friend says that the acceleration has to be negative because the cart is slowing down. The other friend says the acceleration can be positive or negative, but it depends on the motion detector. What do you think and what would you say to your friends to convince them of your point of view
2 answers:
Answer: Acceleration will have 2 components, vertical and horizontal.
Net-vertical component can be positive, zero or negative depending upon the magnitude of the upward component of the applied acceleration.
Net-horizontal acceleration will be equal to the horizontal component of the applied acceleration.
Explanation:
Since acceleration is a vector quantity and the cart is being pushed up the ramp, the ramp would be at some angle to the horizontal and hence there will be vertical and horizontal components of acceleration.
<u>For vertical acceleration:</u>
If the magnitude of the upward component of the applied acceleration is greater than the value of the acceleration due to gravity then the net vertical acceleration will be upward because it will overtake the value of acceleration due to gravity.
In case the upward component of the applied acceleration is lesser than the value of the acceleration due to gravity then the net vertical acceleration will be downward.
<u>For horizontal acceleration:</u>
This component remains unaffected and is equal to the horizontal component of the applied acceleration because there is no other acceleration acting in the horizontal direction.
But the net acceleration will not be solely in the vertical or horizontal direction because the block has to move forward on the inclined ramp so there will always exist a horizontal and a vertical component making the net acceleration to parallel to the ramp in upward direction if the body is going up the ramp.
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Answer:
ρ = 1.6*10⁻⁸ Ω/m.
Explanation:
- Applying Ohm's Law to the wire, assuming that it can be treated as a pure resistance, the resistance of the wire can be obtained as follows:
- At the same time, we know that there exists a relationship between the resistance, the resistivity ρ, the length L and the area A of the wire, that is given for the following expression:
- The area of the circular section of the wire, can be expressed as a function of the diameter d, as follows:
- Replacing the left side of (2) by (1), and (3) on the right side, we can solve for the resistivity ρ as follows:
- ρ = 1.6*10⁻⁸ Ω/m