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Physics problems: kinematics

Part 10

 

Problem 91.

A toy rocket is launched with an initial velocity of 12.0 m/s in the horizontal direction from the roof of a 37.0 m -tall building. The rocket's engine produces a horizontal acceleration of  (time dependent acceleration), in the same direction as the initial velocity, but in the vertical direction the acceleration is , downward.  Air resistance can be neglected. How long is the rocket in the air before it hits the ground?

Solution

 

Problem 92.

A car is moving with a velocity of 72 km/h. It's velocity is reduced to 36 km/h after  covering a distance of 200 m. Calculate its acceleration.

Solution

 

Problem 93.

A car initially at rest, starts moving with a constant acceleration of  and travels a distance of 25 m. Calculate its final velocity.

Solution

 

Problem 94.

An object thrown upwards with a velocity u from the top of a tower of height H reaches the ground in  seconds. When thrown downwards with the same speed it reaches the ground in  seconds. When dropped from the top of tower it reaches in  seconds. Show that .

Solution

 

 

 

 

 

Problem 95.

An airplane is flying due north with a speed relative to the ground of 300 km/h. It then encounters a cross wind that is directed due east. If the resultant speed of the airplane is 310 km/h, how fast is the cross wind?

Solution

 

Problem 96.

A particle  moves along the curve   with constant speed . Express its velocity as a function of (x,y).

Solution

 

Problem 97.

An astronaut jumps from an airplane. After he had fallen 40 m, then his parachute opens. Now he falls with a retardation of  and reaches the earth with a velocity of 3.0 m/s. What was the height of the aeroplane?

Solution

 

Problem 98.

A ball is thrown vertically upward at 20 m/s ignoring air resistance and taking . Calculate:
(1) maximum height.
(2) time taken to reach the maximum height.
(3) time taken to return to starting point.

Solution

 

Problem 99.

Albert is riding his scooter at a velocity of 80 km/h when he sees an old woman crossing the road 45 m away he immediately steps hard on the break to get the maximum deceleration of . How far will he go before stopping, will he hit the old woman?

Solution

 

Problem 100.

A scout travels 5 km south, 3 km east, and 2 north. Find the components of each displacement  and find the final displacement.

Solution

 

 

 

 

 

 

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