Date: ____________________________

SPH4U: Dynamics Part B

Newton’s Second Law

From the above definition of Newton’s second law of motion the acceleration of an object is given by �⃗� =∑�⃗�

𝑚. Typically,

this expression is written as ∑�⃗� = 𝑚�⃗�.

Sample Problem: A young student was working in a factory and had to move a

100 kg box across the room. Being a bright physics student, they realized that they

could reduce the amount of work that they would need to do by using low friction

rollers. Using this information, determine

a. The normal force acting on the box

b. The acceleration of the box.

Sample Problem #2: Consider the image at the right of Kaillie Humphries and Heather

Moyse. Assume that their arms make an angle of 45o with respect to the ground. The

bob sleigh reaches a final speed of 41 km/h during the start. During the start the bob

sleigh travels a distance of 48 m. The bob sleigh has a mass of 173 kg. Assuming the

surface to be nearly frictionless and that both apply equal forces determine

a. The force that each must be applying

b. The normal force acting on the sled

If the external net force on an object is not zero, the

object accelerates in the direction of the net force.

The acceleration is directly proportional to the net

force and inversely proportional to the objects mass.

SPH

4U

Date: ____________________________

SPH4U: Dynamics Part B