By:

This is the obvious information you start with:

**m = 4.5 Kg****F = 18 N**

You have enough information to use the first formula. Using it properly you will arrive at the answer.

Formulas

F = ma

18 N = 4.5 Kg * a

a = 18 N/4.5 Kg

**a = 4 m/s/s**

Go back to: Table of Contents Problem 1

This is the given information:

**F = 256 N****a = 8 m/s/s**

By looking at the given information, you know force, and an acceleration. Therefore you have enough information to use the first formula.

F = ma

256 N = m * 8 m/s/s

m = 256 N/8 m/s/s

**m = 32 Kg**

Go back to: Table of Contents Problem 2

This is the given information:

**m = 250 Kg****a = 3 m/s/s**

By looking at the given information, you know a mass and an acceleration. You are given enough information to use the first formula.

F = ma

F = 250 Kg * 3 m/s/s

**F = 750 N**

Go back to: Table of Contents Problem 3

This is the given information:

**F = 11.2 N****a = 520 m/s/s**

The given information gives you a force and an acceleration. You have enough information to use the first fomula.

F = ma

11.2 N = m * 520 m/s/s

m = 11.2 N/520 m/s/s

m = .0215 Kg

The question asked for mass in grams. The mass right now is in kilograms and must be converted.

Since there are 1000 grams in a kilogram, you must multiply your answer by 1000 to convert to grams.

.0215 Kg * 1000 grams = 21.5 grams

**m = 21.5 grams**

Go back to: Table of Contents Problem 4

This is the given information:

**m = 1400 Kg****V = 30 m/s****t = 4 sec**

The problem gives you a mass, a velocity, and a time. That is not enough information to use a formula.

You should recognize from previous lessons change in that velocity divided by time, equals acceleration.

a = V/t

a = 30 m/s / 4 sec

a = 7.5 m/s/s

These are the variables that you now know.

**m = 1400 Kg****V = 30 m/s****t = 4 sec****a = 7.5 m/s/s**

You now have enough information to use the first formula.

F = ma

F = 1400 Kg * 7.5 m/s/s

**F = 10,500 N**

Go back to: Table of Contents Problem 5

This problem is a continuation of problem # 5. All the information except for time, and acceleration, is equal to problem 5.

This is what you know:**m = 1400 Kg****V = 30 m/s****t = .2 sec**

The problem gives you a mass, a velocity, and a time. That is not enough information to use a fomula.

You should recognize from previous lessons that velocity divided by time, equals acceleration.

a = V/t

a = 30 m/s / .2 sec

a = 150 m/s/s

These are the variables that you now know.

**m = 1400 Kg****V = 30 m/s****t = 4 sec****a = 150 m/s/s**

You now have enough information to use the first formula.

F = ma

F = 1400 Kg * 150 m/s/s

**F = 210,000 N**

Go back to: Table of Contents Problem 6

This is the given information:

**F = 6600 N****V = 27 m/s****t = 4.5 sec**

The problem gives you a force, a velocity, and a time. That is not enough information to use a formula.

You should recognize from previous lessons that velocity divided by time, equals acceleration.

a = V/t

a = 27 m/s / 4.5 sec

a = 6 m/s/s

These are the variables that you now know.

**F = 6600 N****V = 27 m/s****t = 4.5 sec****a = 6 m/s/s**

You now have enough information to use the first formula.

F = ma

6600 N = m * 6 m/s/s

m = 6600 N/6 m/s/s

**m = 1100 Kg**

Go back to: Table of Contents Problem 7

This is what you start with:

**m = 60 Kg****g = 9.8 m/s/s**

Gravity is equal to 9.8 m/s/s because the question does not specify where the person is located. So assume the person is on Earth.

You have enough information to use the second formula.

Formulasw = mg

w = 60 Kg * 9.8 m/s/s

**w = 588 N**

Go back to: Table of Contents Problem 8

This is the given information:

**m = 392 g****g = 9.8 m/s/s**

The mass is given in grams. In order to use the second equation it should be in kilograms, so you must convert.

m = 392 g/1000

m = .392 Kg

This is what you now know:

**m = .392 Kg****g = 9.8 m/s/s**

You now have enough information to use the second equation.

w = mg

w = .392 Kg * 9.8 m/s/s

**w = 3.84 N**

Go back to: Table of Contents Problem 9

This is the given information:

**W = 720 N****g = 9.8 m/s/s****m = 45 Kg****w = 18 N****w = 19.6 N****F = 8 N****g = 9.8 m/s/s****w = 19.6 N****F = 8 N****g = 9.8 m/s/s****m = 2 Kg**

Enough information is given to use the second formula.

w = mg

720 N = m * 9.8 m/s/s

m = 720 N/9.8 m/s/s

**m = 73 Kg**

Go back to: Table of Contents Problem 10

What is the strength of the gravitational force around a planet on a 45 Kg object weighs 18 N? **(.4 N/Kg)**

This is the information given:

You have enough information to use the second formula.

w = mg

18 N = 45 Kg * g

g = 18N/45 Kg

**g = .4 n/Kg**

Go back to: Table of Contents Problem 11

This is the information you know.

Since the object weighs 19.6 N, and it is on earth, you can use the second formula to find it's mass.

w = mg

19.6 N = m * 9.8 m/s/s

m = 19.6 N/9.8 m/s/s

m = 2 Kg

This is the information you have now:

Now you have enough information to use the first formula and finish the problem.

F = ma

8 N = 2 Kg * a

a = 8 N/2 Kg

**a = 4 m/s/s**

Go back to: Table of Contents Problem 12