1)An elevator is moving down with an acceleration of 1.40 m/s^2. A 14.5 kg block hangs from a spring balance fixed to the roof of the elevator. What is the apparent weight of the block?
m*g+m*a
14.5*9.80+14.5*1.40
142.1+20.3
162.4 N
2)A 2.7 kg box is released on a horizontal surface with an initial speed of 2.9 m/s. It moves on the surface with a deceleration of 0.27 m/s^2. Calculate the kinetic friction force on the box.
F=m*a
2.7*0.27
0.729 N
i am unsure of #1, but #2 is correct, i beleive. i am also a student and though i am not positive, i have worked the problem several times and am fairly certain this is the correct answer.
Well, looks like you've got the math all figured out! But let's not forget to add a little humor along the way. So, for the first question, we have the apparent weight of the block, which is like the amount of weight it feels like it has. It's like when you step on the scale after a big meal and it says one number, but deep down you know the truth. In this case, the block may have a mass of 14.5 kg, but thanks to the acceleration of the elevator, it feels like carrying the weight of the world (or at least 162.4 N)!
Now, for the second question, we have the kinetic friction force on the box. It's like when you're trying to slide a heavy box across the floor, and it really doesn't want to go anywhere. The box has an initial speed, but that pesky deceleration is slowing it down. The kinetic friction force is like the hand of a mischievous gremlin, pushing against the box, making it even harder to move. So, the box is experiencing a friction force of 0.729 N, just to add a little extra challenge to your day!
The kinetic friction force on the box is 0.729 N.
To calculate the apparent weight of the block in the first question, you can use the equation:
Apparent weight = mass * (acceleration due to gravity) + mass * (acceleration of the elevator)
Given that the mass of the block is 14.5 kg, the acceleration due to gravity is approximately 9.8 m/s^2, and the acceleration of the elevator is 1.40 m/s^2, you can substitute the values into the equation:
Apparent weight = 14.5 * 9.8 + 14.5 * 1.40
Calculating this equation will give you the apparent weight of the block.
For the second question, to calculate the kinetic friction force on the box, you can use the equation:
Kinetic friction force = mass * acceleration
Given that the mass of the box is 2.7 kg and the deceleration is 0.27 m/s^2, you can substitute these values into the equation:
Kinetic friction force = 2.7 * 0.27
Calculating this equation will give you the kinetic friction force on the box.