Types of forces

Gravity: is a force that pulls an object that has mass into the center of the earth
Friction: is a force that goes in the opposite direction of an sliding object
Balanced force: is when two objects with the same strength are pulling in opposite directions
Unbalanced force: is when two objects that do not have the same strength (one is weaker than the other)are pulling in opposite directions  

How do brakes work?

The hydraulic pressure that reaches each wheel's brake is then used to create friction to slow down and stop the vehicle: the harder you push on the pedal, the more pressure is applied to the brakes, eventually locking the wheels – that is if your vehicle if not equipped with an Antilock Braking System (ABS).

F=MA exercises

1. A car weighs 1000kg, you can push it .05 m/s², how much force (F) are you applying to the car? Here we use F=MA:

F= MA= 1000kg x 0.5 m/s2 = 50 m/s2

2. Another car weighs 2000kg, you can push it .05 m/s², how much force are you applying to the car? Again use F=MA.

F= MA= 2000kg x 0.5 m/s2 = 100m/s2

3. A force of 5000 newtons is applied to a 1200 kg car at rest. What is its acceleration? (m/s²)

A= M/S2= 5000n/1200kg = A: 4.16

4. A 10kg body has an acceleration of 2 m/s². Find the net force (F) acting on the body.

F= MA= 10kg x 2 m/s2 = 20 m/s2

5. An empty truck with a mass of 2500kg has an engine that will accelerate at a rate of 1.5 m/s². What will the force be if the truck is carrying an additional load of 1500kg?

F= MA= 2500kg + 1500kg = 5000kg x 1.5 m/s2 = 7500 m/s2

6. A force of 700 newtons is applied to a 600 kg bowling ball. What is the acceleration of the bowling ball once the force is applied?

A= F/M = 700n/600kg = 1.16

7. A baseball weighs 2.5 kg, after it is hit with a bat it has an acceleration of 36 m/s². How much force was used to make the ball travel that fast?

F= MA= 2.5kg x 36 m/s2 = 90 m/s2

8. During a car crash a bus that weighs 5000kg is hit by a semi truck, the bus moves at a speed of 8m/s². How much force was used to make the bus travel that fast?

F= MA= 5000kg x 8 m/s2 = 40,000 m/s2

9. Mr. G (80kg) is sitting in his favorite desk chair having fallen asleep from all the hard work he does; a disobedient student pushes Mr. G down the hall with an acceleration of 10 m/s². How much force would the student have to use to get Mr. G to move that fast?

F= MA= 80kg x 10 m/s2 = 800 m/s2

10. An old mousetrap car is sprung into motion and weighs 1000 kg. It is pulling a trailer with 1750 kg on it, travels with an acceleration of 20 m/s². What was the force of the mousetrap that enabled the car to move that fast?

F= MA= 1000kg + 1750kg = 2750kg x 20 m/s2 = 55,000 m/s2