Scientific unit
and measurements
and measurements
Formula for kinetic energy
1/2*mass*(velocity) squared
State Newton's law of linear motion
Newton's first law of motion states that a body at rest remains at rest and a body in motion remains in motion in a straight line except an external force acts on it.
Newton's second law of motion states that the time rate of change of momentum is directly proportional to the force applied and it takes the place of the direction of the force.
Newton's third law of motion states that for every action there is an equal and opposite reaction.
Define tensile stress
It is the ratio of the tensional force to the cross sectional area
What is centripetal force?
It is the force that acts on a body in circular motion and is directed towards the centre of the path.
Define gravitational potential
It is the work done in bringing a body of unit mass from infinity to a point of gravitational field
Formula for density
Density=mass per unit volume
a) What is a contact force?
b)Give two examples of contact forces.
a)A contact force is a force between two bodies which results in changing the shape or the motion of the bodies involved
b)-Friction
-Thrust
State three different materials that can be used to demonstrate Brownian motion
*Smoke particles
*Chalk particles
*Pollen grains
Explain why roads are banked at the bends
*At unbanked roads frictional force required to keep a vehicle in a circular path is not sufficient
*Banking provides an additional force due to the normal reaction on the wheels to prevent the vehicle from slipping
Define escape velocity
It is the minimum velocity required by an object on the surface of the earth to leave the gravitational attraction of the earth (planet)
Formula for work
Work =force*distance
State the principle of linear motion
It states that if no external forces act on a system of colliding objects,the total momentum of the objects before collision is equal to the total momentum of collision.
Explain the term Young's modulus
It is the ratio of tensile stress to tensile staring. It is expressed in Nm/2
Define uniform acceleration
It is the constant time rate of increase with velocity
A spacecraft is launched with an initial velocity greater than the escape velocity.What is the shape of it's trajectory?
A parabola
Formula for momentum
Mass*velocity
Define an elastic collision.
Elastic collision is a collision in which there is no loss of kinetic energy or kinetic energy is conserved.
Define diffusion in relation to gases
It is the mixing of a gas with another to fill an empty space as a result of constant random motion of their molecules.
Write an equation that relates linear velocity, angular velocity and radius of path in circular motion
Linear velocity=angular velocity*radius of path
State two uses of satellites
For navigation
Weather forecasting
Formula for impulse
Force*time
List three uses of rockets
*For space exploration
*Warfare (to launch missiles
*Scientific research
State three evidences that support the particle nature of matter
*Brownian motion
*Surface tension
*Osmot
Define angular acceleration
It is the time rate of change of angular velocity of a body undergoing circular motion
Explain the term acceleration of free fall
It is the force per unit mass acting vertically downwards in the Earth's gravitational field.It is a vector quantity.