# Homework Help: How much force and energy for moving a frictionless object

1. Jan 31, 2016

### 5P@N

1. The problem statement, all variables and given/known data
I have an object of 10 kg
It is to be displaced 2 meters
Assume a frictionless surface, and no wind resistance
The object begins as stationary, then is moved that distance in the span of .5 seconds.

2. Relevant equations
Force = mass* acceleration
acceleration = (delta velocity) / time
velocity = (delta position) / time

3. The attempt at a solution
initial velocity is 0
final velocity is: (2 - 0) meters / .5 second = 2 meters / .5 seconds= 4 meters per second
acceleration = (4 m/s - 0 m/s) / .5 seconds = 8 meters / second^2
8(m/s^2) * 10 kg = 80 Newtons

Correct?

2. Jan 31, 2016

### haruspex

You have mot stated what you are asked to find. You seem to have assumed a constant force. Is that given?

3. Jan 31, 2016

### Staff: Mentor

Are you told to assume a constant force?

4. Jan 31, 2016

### haruspex

You have not provided the whole question. What exactly are you supposed to find? Minimum energy? Least maximum magnitude force?
As berkeman posted, you seem to have assumed a constant force, but even then your calculation is wrong:
That calculates the average speed, not the final speed. Check your answer: constant acceleration of 8m/s2 for 0.5 seconds from rest would travel how far?

5. Jan 31, 2016

### 5P@N

What do you all mean when you say: "constant force"?

What would this constant force do? What are its attributes?

.5^2 = .25
.25 *8 = 2
since the object moved 2 meters, this appears correct. Or what am I missing?

6. Jan 31, 2016

### haruspex

Review the equation relating time, distance, initial speed, and constant acceleration. You are missing something.

Please state the entire question, exactly as presented to you.