Newton’s Laws 10min test q1 Motion direction pull Weight (force due to gravity – don’t just...
-
Upload
chastity-conley -
Category
Documents
-
view
217 -
download
0
Transcript of Newton’s Laws 10min test q1 Motion direction pull Weight (force due to gravity – don’t just...
Newton’s Laws 10min test
• q1Motion direction
pull
Weight (force due to gravity – don’t just say ‘gravity’)
Friction (opposite to the motion)
Contact force
Show forces as pulls, not pushes in these diagrams, and show object as a point or a box
1c
• If the object is accelerating, either getting faster or slower, then one forces must be bigger than the force opposite to it.
q2
• Newton’s first law:
• if there is no resultant force acting on an object then it will not change its velocity
• (that means it will stay at rest or, if already moving, will continue in a straight line at a steady speed)
q3
• Newton’s second law:
• If there is a resultant force acting on an object then it will change its velocity
• That means it will either get faster or slower or it will change its direction of motion. This law gives us an equation:
• F=ma where F is the resultant force and ‘a’ is the acceleration that the mass m has
q4
• Pull = 20N, Friction = 6N
• So resultant force = 20-6 = 14N
• Mass = 7kg
• F=ma gives us 14 = 7a
•
• so acceleration a = 2m/s2
q5• Mass is the amount of substance in a body
• Weight is the force of the earth’s gravity pulling the mass downwards
• b) Using F=ma we have
• Weight = mass x 10 because gravity always accelerates mass at 10m/s2 on the earth (called g). But mass has to be in kg
• So 300g (0.3kg) has a weight of 3N