# Free Fall

## Trending Questions

**Q.**

If the value of $G$ (universal gravitational constant) is $6.67\times {10}^{-11}$ unit, then determine the value in CGS system.

**Q.**

The area under a $v\u2013t$ graph represents a physical quantity that has the unit

${m}^{2}$

$m$

${m}^{3}$

$\frac{m}{s}$

**Q.**

If a ball is thrown vertically upwards with $40m/s$ its velocity after two seconds will be:-

**Q.**

Why at the centre of earth gravitational force is zero .is it because r=0 or the mass of earth at that point is zero?

**Q.**Derivation of s=ut+1/2(gt

^{2}

**Q.**

Why is G called the universal constant?

**Q.**

How does the value of ‘g’ change as one goes up above the surface of the earth?

**Q.**

Name the force which is holding the atmosphere to the earth.

**Q.**

A satellite of mass m revolves around the earth of radius R at a height x from its surface. If g is the acceleration due to gravity on the surface of the earth, the orbital speed of the satellite is

gx

$\frac{gR}{R-x}$

$\frac{g{R}^{2}}{R+x}$

${\left(\frac{g{R}^{2}}{R+x}\right)}^{\frac{1}{2}}$

**Q.**

area under distance - time graph gives

**Q.**

In which of the following graphs are both runners moving at the same speed?

Graph-A

Graph-D

Graph-B

Graph-C

**Q.**

A stone is falling freely and describes a distance $S$ in $t$ seconds given by equation $S=\frac{1}{2}g{t}^{2}$. The acceleration of the stone is

Uniform

Zero

Non–uniform

Indeterminate

**Q.**

A body falls from a height of 500 m. In how much time, will it strike the ground ? (Give the answer in seconds)

**Q.**

The magnitude of gravitational force between the earth and 10 kg body is:

98 N

9.8 N

90 N

100 N

**Q.**

A uniform chain of length L and mass M is lying on a smooth table and one-third of its length is hanging vertically down over the edge of the table. If g is acceleration due to gravity, the work required to pull the hanging part on to the table is

**Q.**

Distance-time graph of two objects A and B are shown below.

Which statement is true for the speed of object A and B?

Speed of object A is greater than object B

Speed of object A is smaller than object B

Both have same speed

Speed of Object A is double the speed of object B.

**Q.**

Figure below shows the distance-time graph of three objects A, B and C. Find the speed of all the three bodies. Which of the following three is travelling the fastest? [3 MARKS]

**Q.**Starting from rest a car accelerates uniformly with 3meter per second square for 5sec and then moved with uniform velocity draw distance time graph of the motion of the car up to t=7sec

**Q.**

In the given velocity-time graph, AB shows that the body has

uniform acceleration

uniform retardation

uniform velocity throughout its motion and has zero initial velocity

none of these

**Q.**

If the ratio of the masses of two planets is 2:3 and the ratio of their radii is 4:7 then the inverse ratio of their acceleration due to gravity will be

49:24

24:49

7:8

8:7

**Q.**

Identical packets are dropped from two airplanes, one above the equator and the other above the north pole, both at height $h$. Assuming all conditions are identical, will those packets take the same time to reach the surface of the earth. Justify your answer.

**Q.**

The escape velocity of an object on a planet whose $g$ value is $9times$ on earth and whose radius is $4times$ that of the earth in km/s is

$67.2$

$33.6$

$16.8$

$25.2$

**Q.**

Write four phenomena that were successfully explained using the universal law of gravitation.

**Q.**A crumpled paper and a feather are dropped from the top of a building at the same time. Neglecting the air resistance, which one of them would reach the ground first?

- Both would reach at the same time.
- Data insufficient to determine
- The feather
- The crumpled paper

**Q.**

What do you mean by acceleration? How do you find acceleration from velocity-time graph?

**Q.**

Acceleration due to gravity of a body is independent of

mass of the body

altitude of the body

latitude of the body

depth below the earths surface

**Q.**1. Write the three equation of motion for freely falling bodies and write the value of g.

2. A cricket ball is dropped from a height of 20 metres. [5 MARKS]

(a) Calculate the speed of the ball when it hits the ground

(b) Calculate the time it takes to fall through this height.

**Q.**

Identify free fall situations from the following.

A man landing with a parachute.

An apple falling on the Moon.

A rocket propelling into space.

A block falling from a cliff.

**Q.**While playing, Ria's brother Vedant throws a ball upwards with a speed of 20 m/s . Find the total time of a ball in the air, take acceleration due to gravity, g=10 ms−2

- 8 seconds
- 4 seconds
- 6 seconds
- 2 seconds

**Q.**

Distance-time graph of two objects A and B are shown below.

Speed of object A is smaller than object B

Speed of object A is greater than object B

Speed of Object A is double the speed of object B.

Both have same speed