Net Force
A 12kg block is accelerated 3m/s2. What is the net force on the block?
36N
The net force on a 3kg block is 21N. What is the block's acceleration?
7m/s2
A block experiences a net force of 10N and accelerates 5m/s2. What is the block's mass?
2kg
The forces on an object are unbalanced. Must the object be accelerating?
Yes
A 2kg book is placed on a shelf 3m high. What is the potential energy of the book?
PE= (9.8)(2)(3)= 58.8J
A 6.27kg chair is accelerated 4.35m/s2. What is the net force on the chair (to three significant figures)?
27.3N
The net force on a 1250kg car is 5670N. What is the car's acceleration (to three significant figures)?
4.54m/s2
A bookshelf experiences a net force of 40.2N and accelerates 2.19m/s2. What is the bookshelf's mass (to three significant figures)?
18.4kg
The forces on an object are balanced. Could the object be moving?
Yes
A sled and it's rider speed down a 30m hill. The sled and the rider have a combined mass of 100 kg. What is the kinetic energy at the bottom of the hill, just before they stop moving?
KE= 0.5(100)(30)(30)= 45,000 J
A 10g ball accelerates 5m/s2 down a slope. What is the net force on the ball?
0.05N
A 50g model rocket experiences a net force of 5N. What is the model rocket's acceleration?
100m/s2
A jet experiences 120kN (120 kilonewtons) of net force and accelerates 3m/s2. What is the jet's mass?
40,000kg
An object's acceleration is ______ proportional to its net force.
directly
A bird sits at the top of the empire state building, that stands 270m tall. The bird has a mass of 17 kg, and can fly at a top speed of 5.7 m/s. What is the kinetic energy of the bird?
Not moving= 0 J
A 45.6g golf ball is accelerated 10.5m/s2. What is the net force on the golf ball (to three significant figures)?
0.479N
A 565,000kg rocket experiences a net force of 13,500kN (13,500 kilonewtons). What is the rocket's acceleration (to three significant figures)?
23.9m/s2
A steam locomotive experiences a net force of 113kN (113 kilonewtons) and accelerates at a rate of 1.67m/s2. What is the steam locomotive's mass (to three significant figures)?
67,700kg
An object's acceleration is ______ proportional to its mass.
inversely
If a 1 kg bouncy ball, bounces to a height of 2 m at a speed of 6m/s. What is the Mechanical Energy of the bouncy ball?
ME= KE + PE
KE = 0.5(1)(6)(6)= 18 J
PE= 9.8(1)(2)= 19.6 J
ME= 18+19.6= 37.6 J
A 71.3kg man sits on a 900g skateboard and accelerates 5.28m/s2 down a slope. What is the net force on the man & skateboard system (to three significant figures)?
381N
A 755g toy is being pushed 6.43N along the ground and experiences 2.34N of kinetic friction. What is the toy's acceleration (to three significant figures)?
5.42m/s2
A net force of 10.5N accelerates a block from rest to a speed of 15.2m/s in the span of 3.01s. What is the block's mass (to three significant figures)?
2.08kg
An object's mass is ______ proportional to its acceleration.
inversely
A skydiver has a mass of 80 kg, and jumps from a height of 3000 m. What is the kinetic energy of the skydiver just before they hit the ground?
At the top PE= (9.8)(80)(3000)= 2,352,000J and KE= 0J
At the bottom these flip for PE= 0J and
KE= 2,352,000 J