MET 110 : Dynamics
Sample problems
1.) A net force of 7.5 kN, west acts on a 1208 kg race car.
= 6.2 m/s2, west)
At what rate will the car accelerate?
(a
2.) A car, mass 1485 kg, travelling south at 116 km/h, slows to a stop in 10.25 seconds.
What is
the magnitude and direction of the net force that acted on the truck?
(F = 4.67 kN, north)
3.) Find the net force acting on a fridge if the applied forces are 378.4 N, west
while the force of friction is 67 N. (FNet = 713 N, west)
and 401.3 N, west
4.) A large box moving across a floor at constant speed has two people moving it. One is pushing
236.1 N from behind while the other is pulling 89.3 N from the front. What is the force of
friction? (Ff = 325.4 N, opposite to the direction of motion)
5.) Find the acceleration of a 20.0 kg curling stone if the applied force is 88.7 N, west
force of friction is 29.73 N. (a = 2.95 m/s2, west)
and the
6.) Find the weight (force of gravity) of an exactly thirty kilogram mass. (Fg = 294 N, down)
7.) A broken down car, mass 1418 kg, is accelerated at 1.65 m/s2, south when pulled by a tow truck.
What is the force of friction if the tow truck exerts 2.63 kN, south on the car?
(Ff = 0.29 kN,
north)
8.) A 5.0 kilogram mass lays on a floor. What force does the floor exert on the object?
upward)
(FA = 49 N,
9.) A cannon of mass 425 kg shoots a 3.75 kg ball with a force of 0.862 kN, south. Find the
acceleration of both the cannon and the ball ignoring friction.
( acannon = 2.03 m/s2, north
; aball = 230 m/s2, south )
10.) A 55.0 kg woman climbs at a constant velocity up a rope. a) What force does the rope exert
on the woman? ( FA = 539 N, upward ) b) What force does the woman exert on the rope? ( FA =
539 N, downward ) c) How would the answers to a) and b) change if she was descending?
11.) A 4850 kg helicopter accelerates downward at 1.58 m/s2.
the propellers? ( FA = 39.9 kN, upward )
What force is exerted by the air on
12.) A horizontal force of 26.3 N is necessary to push a 99 N wooden box across a tile floor
at constant velocity. Find the coefficient of sliding friction between the two surfaces.
( μ = 0.27 )
13.) The coefficient of sliding friction between rubber tires and wet pavement is 0.65.
The brakes are applied to a 1000 kg car traveling west and it skids to a stop.
Find the force of friction the road exerts on the car. ( Ff = 6.3 kN, east )