Determine the magnitude of the current flowing through a 4.7 kilo ohms resistor if the voltage across it is (a) 1mV (b) 10 V (c)
1 answer:
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Answer:
A) v = 28.3 m/s
B) t = 4.64 s
Explanation:
A)
- Assuming no other forces acting on the rock, since the accelerarion due to gravity close to the surface to the Earth can be taken as constant, we can use one of the kinematic equations in order to get first the maximum height (over the roof level) that the ball reaches:
- Taking into account that at this point, the speed of the rock is just zero, this means vf=0 in (1), so replacing by the givens and solving for Δh, we get:
- So, we can use now the same equation, taking into account that the initial speed is zero (when it starts falling from the maximum height) and that the total vertical displacement is the distance between the roof level and the ground (26.0 m) plus the maximum height that we have just found in (2) , 14.8m:
- Δh = 26.0 m + 14. 8 m = 40.8 m (3)
- Replacing now in (1), we can solve for vf, as follows:
B)
- In order to find the total elapsed from when the rock is thrown until it hits the street, we can divide this time in two parts:
- 1) Time elapsed from the the rock is thrown, until it reaches to its maximum height, when vf =0
- 2) Time elapsed from this point until it hits the street, with vo=0.
- For the first part, we can simply use the definition of acceleration (g in this case), making vf =0, as follows:
- Replacing by the givens in (5) and solving for Δt, we get:
- For the second part, since we know the total vertical displacement from (3), and that vo = 0 since it starts to fall, we can use the kinematic equation for displacement, as follows:
- Replacing by the givens and solving for t in (7), we get:
- So, total time is just the sum of (6) and (8):
- t = 2.9 s + 1.74 s = 4.64 s
Answer:
Explanation:
Given
mass of car
Initial velocity of car towards east
Time taken to stop
Force exerted
change in momentum is given by impulse imparted to the car
negative Sign indicates that impulse is imparted opposite to the direction of motion
magnitude of momentum