Assignment:
Acceleration & Force :
Question 1. Calculate the average acceleration of a car that changes speed from 0 m/s to 15 m/s in 5 s.
Question 2. Suggest why placing wheels under a heavy box reduces the necessary force required to push it along at a constant speed.
Question 3. Evaluate the change of motion in the following cases in which the forces on an object change from balanced to unbalanced.
a. The brake of a car parked on a hill is released.
b. A skydriver falling at a constant speed opens her parachute.
c. A boat moving at a constant speed of 44 km/h enters a crosswind.
Newtons's Laws of Motion:
Question 1. Calculate the acceleration of a 82kg couch that is pushed across the floor with an unbalanced force of 21 N.
Question 2. Explain why free-fall acceleration can be regarded as a constant for objects falling within a few hundred meters of Earth's surface.
Question 3. Apply Newton's first and second laws to explain why an object moving in a circular path at a constant speed is undergoing acceleration and has a force exerted on it.
Question 4. Apply Newton's third law of motion to explain how two billiard balls moving toward each other at the same speed collide and move away from each other at the same speed as before.
Question 5. Identify which of Newton's three laws of motion specifically applies in each of the following situations:
a. You feel a force against the sole of your foot as you take a step forward.
b. A meteror moving in a straight path changes direction when it flies by Earth.
c. A full grocery cart that is pushed starts moving and increases speed, but the same push increases its speed even more when the cart is empty.
d. a skateboard moves faster in the same direction it is pushed.