18 terms

# Unit 4 Week 2 Problem Set

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A 1500 kg car accelerates from 0 to 25 m/s in 7.0 s. What is the average power delivered by the engine? (1hp=746 W)
90 hp
A cyclist does work at the rate of 500 W while riding. How much force does her foot push with when she is riding at 8.0 m/s?
63 N
How many joules of energy are used by a 1.0 hp motor that runs for 1.0 hr? (1hp=746 W)
2.7x10^6 J
A 10-N force is needed to move an object with a constant velocity of 5.0 m/s. What power must be delivered to the object by the force?
50 W
At what rate is a 60.0 kg boy using energy when he runs up a flight of stairs 10.0 m high in 8.00s?
735 W
A roller coaster starts from rest at a point 45 m above the bottom of a dip. Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?
17 m/s
A roller coaster starts with a speed of 5.0 m/s at a point 45 m above the bottom of a dip. Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 30 m above the bottom of the dip?
18 m/s
A roller coaster starts at a point 30 m above the bottom of a dip with a speed of 25 m/s. Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the next dip?
18 m/s
A pendulum of length 50 cm is pulled 30 cm away from the vertical axis and released from rest. What will be its speed at the bottom of the swing?
1.4 m/s
A 1500 kg car moving at 25 m/s hits an initially uncompressed horizontal spring with spring constant 2.0x10^6 N/m. What is the maximum compression of the spring? (Neglect mass of spring)
0.68 m
A driver, traveling at 22 m/s, slows down her 2000 kg car to stop for a red light. What work is done by the friction force against the wheels?
-4.84x10^5 J
The kinetic friction force between a 60 kg object and ahorizontal surface is 50 N. If the initial speed of the object is 25 m/s, what distance will it slide before coming to a stop?
375 m
A 60-kg skier starts from rest from teh top of a 50-m high slope. If the work done by friction is -6x10^3 J what is the speed of the skier on reaching the bottom of the slope?
34 m/s
An 800 N box is pushed up an inclined plane. The plane is 4.0 m long and rises 2 m. It requires 3200 J of work to get the box to the top of the plane. What was the magnitude of the average friction force on the box?
400N
A toy rocket, weighing 10 N, blasts straight up from ground level with a kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height does it rise?
14m
A 1.0 kg ball falls to the floor. When it is 0.7 m above the floor, its potential energy exactly equals its kinetic energy. How fast is it moving?
3.7 m/s
A skier, with mass of 40 kg, pushes off the top of a hill with an initial speed of 4 m/s. Neglecting friction, how fast will she be moving after dropping 10 m in elevation?
15 m/s
A 400 N box is pushed up an inclined plane. The plane is 4 m long and rises 2 m. If the plane is frictionless, how much work was done by the push?
800 J