What is the magnitude of the thrust force before the cart is released?Express your answer in newtons using three significant figures.

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In this video, a small cart that has a mass of 600 grams rests on a table top. There is a fan on top of the cart, blowing air backwards at a steady rate. A stretched spring is attached to the back of the cart by a string, holding it in place. A scale, marked off in newtons, is positioned next to the spring and a small dot at the end of the spring indicates the magnitude of the spring force. The spring and scale together is called a “dynamometer.” Before the cart is released from the spring, the dynamometer reads approximately 1.9 newtons. The video is recorded at 60 frames per second, resulting in playback motion 2 times slower than normal. A frame counter indicates the current frame. A horizontal distance scale, marked off in centimeters, is also shown on the video. While the cart is at rest, the front edge of the front wheel is at the zero of the scale.

At frame 245, the string that attaches the cart to the spring is cut, releasing the cart, and it begins to roll forward. Using the distance scale, the position of the front edge of the front wheel can be tracked with

time. The following table indicates the position at different frames.

Frame            Position (cm)

245                  0.0

251                   1.9

257                  6.0

263                  13.9

269                  24.6

275                 38.4

281                  55.1

287                 75.0

Answer : 1.9 N

Explanation:

The magnitude of the thrust force before the cart is released can be calculated as :

60 fbs = 1 frame = 1/60 secs

therefore 6 frames = 1 / 10 secs

F fam = F spring = 1.9 N

Note: F thrust = F fam = 1.9 N

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.

i guess it’s a and b