Forces
What are Newton's Laws?
1. A body at rest/motion stays in that state until acted on by another force
2. F = ma
3. Equal and Opposite reaction
A force of 15 N is applied at a 60° angle to an object that moves 3 m. How much work is done?
22.5 J
a 1500kg vehicle hits an uncompressed spring at 25 m/s. The spring compresses by 0.685 meters. What is the spring constant?
2E6 N/m
If something has a height of 62.5 meters, and a mass of 5 kg, what is its Gravitational Potential Energy?
3062.5 J
If a net force of 18 N acts on a 3 kg object, what is the object’s acceleration?
6 m/s^2
A force of 50 N is applied to move a box 4 m, but 20 N of friction opposes the motion. What is the net work done?
120 J
On a banked curve, what force acts as the centripetal force?
Static Friction
A 500kg rollercoaster cart starts from rest at a height of 20 m. Assuming no friction, how fast is it going when it reaches 5 m?
17.15 m/s
\sqrt{\frac{73500}{500\cdot.5}}
A block of mass 3m can move without friction on a horizontal table. This block is attached to another block of mass m by a cord that passes over a frictionless pulley. What is the magnitude of the acceleration of the descending block?
g/4
A car moving at 20 m/s applies brakes and stops in 4 s. What is the work done if its mass is 1500 kg?
-300,000 J
An 800 kg satellite is in circular orbit 300 km above Earth's surface. (Earth's radius = 6400 km, G=6.67×10^−11). What is the gravitational force acting on it?
7100 N, through the use of F = Gm1m2 / r^2
A ball hangs from a string of negligible mass. What is the minimum speed that the ball must have at the bottom of the swing to reach a height of 1m above the ground on it's swing up.
4.427 m/s
An elevator accelerates upward at 2 m/s². If you have a mass of 60 kg, what is the normal force acting on you?
708 N
A person pushes a 20 kg box 5 meters across a floor at constant speed by applying a force of 60 N at an angle of 37° below the horizontal. How much work is done by the applied force?
240 J
A Ferris wheel rotates at a constant speed. At the top of the ride, your apparent weight feels less. Why?
The normal force has decreased in comparison to the weight force, allowing for downward acceleration
A 4 kg block is pushed along a frictionless track, up a hill of height 6 m, starting with a speed of 15 m/s. Does it reach the top?
yes
initial KE is 450 J; initial PE is 0
final PE is 235.2; leftover KE is roughly 214.8
Two blocks are connected by a string through an ideal pulley. Block A is 5kg and is on a 40 degree incline plane with a uk of 0.25. Block B is 4.8kg. Find acceleration.
0.628 m/s^2
A 50 kg crate is pulled up a rough incline (10 m long, 30° incline) with a constant speed. The friction coefficient is 0.05. How much total work is done against gravity and friction?
2450 + 212
2662 J
A person of mass 70 kg rides a Ferris wheel of radius 20 m, moving at 4 m/s.
Find the normal force at the top of the ride.
630 N
To store 1000 J of energy in a spring when it is compressed by .25 m, what does the spring constant need to be?
32000 N/m