Motion basics
Uniform Motion
Newton's Laws
Miscellaneous
100
What is the relationship between velocity and acceleration?

Acceleration is the change (slope) in velocity.

100

A rocketship accelerates uniformly from rest, and after 5 seconds it has travelled 2000 meters. What is its average acceleration?

s = ut + (1/2)at2

2000 = (0)(5) +(1/2)(a)(5)2

a = 12.65 m/s2

100

What is inertia, in the context of Newton's first law?

The resistance of an object to a change in its velocity. The tendency of objects to keep moving in a straight line, when no external forces are acting on them.
100
What is the difference between mass and weight?

Mass is the amount of matter in an object, while weight is the gravitational force exerted on the object.

200

What is the difference between speed and velocity?

Speed is scalar (direction-independent) while velocity is vector (direction-dependent).

200

A rocket, initially at rest, accelerates at 20 m/s2, for 8 seconds. What is its instantaneous velocity at 8 seconds.

v = u + at

v = 0 + (20)(8)

v = 160 m/s

200

What is the magnitude of a force that accelerates a 12 kg object up a hill at 6 m/s2?

72 Newtons

200

In a totally inelastic collision, and in the absence of friction, if a car moving 10 m/s collides with another stopped car of the same mass, at what velocity will they be moving after the crash?

Together at 5 m/s

300

A 10,000 kg spaceship is hovering 600 meters above New York City, what is its gravitational potential energy?

PE = mgh 

PE = (10,000)(10)(600)

PE 60,000,000 J

300

If a plane is accelerating down a runway at 4.5 m/s, from rest, how long will it take to reach the end of the 200 meter runway?

s = ut + (1/2)at2

t = 9.43 seconds

300

If a large man and a small woman on roller skates push off each other, who will gain the greater velocity?

The woman

300

If a 60 kg man jumps up in the air, and in 0.1 seconds reachers a height of 1.5 meters, what was his takeoff speed?

KE = PE (conservation of energy)

(1/2)mv2 = mgh 


v = (2gh)1/2  = (2 x 10 x 1.5)1/2

v = 5.477 m/s 


400

If a 2000 kg car is moving 60 mph down a highway, what is its kinetic energy?

KE = (1/2)mv2

KE = (1/2)(2000)(60)2

= 3,600,000 J
400

A UFO is moving at 20 m/s, then accelerates for 10 seconds to 80 m/s. How far did the UFO move in those ten seconds??

s = ((u+v)/2)t

s = ((20 + 80)/2)10

s = 500 meters

400

How does Newton's third law explain how a car accelerates?

The engine turns the wheels, and the wheels push on the ground. This force is mirrored by the ground to the car, accelerating the car.

400

If a 60 kg man jumps up in the air, and in 0.1 seconds reachers a height of 1.5 meters, what amount of power did he develop?

Power = (mgh)/t

Power = (60 x 10 x 1.5) / 0.1

Power = 9000 W

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