Solve Physics Problems: 3 Little Questions

[anthonyy]

Hi everyone, I've justed started work, force, kenetic, poteintial, and acceleration over these days and I've come across these problems, some which I don't understand. I hope you guys can help out.

1) A car traveling initailly @ 26.9 m/s comes to a stop in 2.61s. The masss of the car w/ the driver is 1180 kg. Calculate the acceleration and the net force required to cause that acceleration

2) The force of gravity on a 251 kg spacecraft on the Moon's surface is 408 N. What is the acceleation of a free-falling object on the surface of the moon?

3) The heaveist person in history is about 6.2 kN. Determine the mass of this record holder in kilograms.

*If I'm not mistaken, the answer to question #3 should be 632 kg, right?

It would be best if you could show me the steps to get to the answer.

Many, many thanks,

 

[whozum]

https://www.physicsforums.com/showthread.php?t=28" might be of concern to you.

1 follows directly from definitions of average acceleration, velocity, and Newton's laws.
2 just requires Newton's 2nd Law
3 is 633kg, review significant figures.

 

[thepatientmental]

Hi there! I'd be happy to help you with these physics problems. Let's take a look at each one and see if we can figure them out together.

1) To solve this problem, we can use the equation a = (vf - vi)/t, where a is acceleration, vf is final velocity, vi is initial velocity, and t is time. We are given the initial velocity (vi = 26.9 m/s) and the time (t = 2.61 s), so we just need to find the final velocity.

To find the final velocity, we can use the equation vf = vi + at. Plugging in our known values, we get vf = 26.9 m/s + a(2.61 s). We also know the mass of the car (m = 1180 kg), so we can use Newton's second law, F = ma, to find the net force required.

Solving for a, we get a = (vf - vi)/t = (0 - 26.9 m/s)/2.61 s = -10.3 m/s^2. This is the acceleration of the car as it comes to a stop.

To find the net force, we can plug our calculated acceleration into F = ma. So, F = (1180 kg)(-10.3 m/s^2) = -12,154 N. The negative sign indicates that the force is in the opposite direction of motion (since the car is decelerating).

2) To solve this problem, we can use the equation F = ma. We are given the mass (m = 251 kg) and the force of gravity (F = 408 N). So, we can rearrange the equation to solve for acceleration, a = F/m.

Plugging in our known values, we get a = 408 N/251 kg = 1.63 m/s^2. This is the acceleration of a free-falling object on the surface of the moon.

3) Yes, you are correct! The heaviest person in history was Jon Brower Minnoch, who weighed approximately 6.2 kN. To find his mass in kilograms, we can use the equation F = ma. Since we know the force (F = 6.2 kN) and the acceleration due to gravity (a = 9.8 m/s^2), we can rearrange the equation to solve