Improvement in Food Resources — Science STD 9 — Question

A car is moving along a straight road at a steady speed. It travels 150m in 5 seconds:
How far does it travel in 1 second?

A boy weighing 40kg carries a box weighing 20kg to the top of a building 15m high in 25 seconds. Calculate the power. (g = 10m/s²)

Why does steam cause more severe burns than boiling water?

Two objects, each of mass 1.5kg, are moving in the same straight line but in opposite directions. The velocity of each object is 2.5m s^-1 before the collision during which they stick together. What will be the velocity of the combined object after collision?

When water is cooled to a temperature x, it gets converted into ice at temperature x by a process called P. And when ice at temperature x is warmed, it gets reconverted into water at the same temperature x in a process called Q.

1. What is the value of temperature x in Kelvin?
2. What is the process P known as?
3. What is the name of energy released during process P?
4. What is the process Q known as?
5. What is the name of energy absorbed during process Q?

What would you observe when:
A mixture of iron filings and sulphur powder is heated strongly.

“Lysosomes are known as suicide bags.” Why?

Why are road accidents at high speeds very much worse than road accidents at low speeds?

In loading a truck, a man lifts boxes of 100N each through a height of 1.5m.

1. How much work does he do in lifting one box?
2. How much energy is transferred when one box is lifted?
3. If the man lifts 4 boxes per minute, at what is he working? (g = 10 ms^-2)

Where are proteins synthesised inside the cell?